Harr CC Flashcards
Which formula correctly describes the relationship between absorbance and %T ?
A. A = 2 – log %T
B. A = log 1/T
C. A = –log T
D. All of these options
D. All of these options
Absorbance is proportional to the inverse log of transmittance.
A = –log T = log 1/T
Multiplying the numerator and denominator by 100 gives:
A = log (100/100 X T)
100 X T = %T, substituting %T
for 100 X T gives:
A = log 100/%T
A = log 100 – log %T
A = 2.0 – log %T
For example, if %T = 10.0, then:
A = 2.0 – log 10.0
log 10.0 = 1.0
A = 2.0–1.0 = 1.0
A solution that has a transmittance of 1.0 %T would have an absorbance of:
A. 1.0
B. 2.0
C. 1%
D. 99%
B. 2.0
A = 2.0 – log %T
A = 2.0 – log 1.0
The log of 1.0 = 0
A = 2.0
In absorption spectrophotometry:
A. Absorbance is directly proportional to transmittance
B. Percent transmittance is directly proportional to concentration
C. Percent transmittance is directly proportional to the light path length
D. Absorbance is directly proportional to concentration
D. Absorbance is directly proportional to
concentration
Which wavelength would be absorbed strongly by a red-colored solution?
A. 450 nm
B. 585 nm
C. 600 nm
D. 650 nm
A. 450 nm
A green-colored solution would show highest transmittance at:
A. 475 nm
B. 525 nm
C. 585 nm
D. 620 nm
B. 525 nm
SITUATION: A technologist is performing an enzyme assay at 340 nm using a visible-range
spectrophotometer. After setting the wavelength and adjusting the readout to zero %T with the light path blocked, a cuvette with deionized water is inserted. With the light path fully open and the 100%T control at maximum, the instrument readout will not rise above 90%T. What is the most appropriate first course of action?
A. Replace the source lamp
B. Insert a wider cuvette into the light path
C. Measure the voltage across the lamp terminals
D. Replace the instrument fuse
A. Replace the source lamp
Which type of monochromator produces the purest monochromatic light in the UV range?
A. A diffraction grating and a fixed exit slit
B. A sharp cutoff filter and a variable exit slit
C. Interference filters and a variable exit slit
D. A prism and a variable exit slit
D. A prism and a variable exit slit
Which monochromator specification is required in order to measure the true absorbance of a
compound having a natural absorption bandwidth of 30 nm?
A. 50-nm bandpass
B. 25-nm bandpass
C. 15-nm bandpass
D. 5-nm bandpass
D. 5-nm bandpass
Which photodetector is most sensitive to low levels of light?
A. Barrier layer cell
B. Photodiode
C. Diode array
D. Photomultiplier tube
D. Photomultiplier tube
Which condition is a common cause of stray light?
A. Unstable source lamp voltage
B. Improper wavelength calibration
C. Dispersion from second-order spectra
D. Misaligned source lamp
C. Dispersion from second-order spectra
A linearity study is performed on a visible spectrophotometer at 650 nm and the following
absorbance readings are obtained:
Concentration of Standard Absorbance
10.0 mg/dL 0.20
20.0 mg/dL 0.41
30.0 mg/dL 0.62
40.0 mg/dL 0.79
50.0 mg/dL 0.92
The study was repeated using freshly prepared standards and reagents, but results were identical
to those shown. What is the most likely cause of these results?
A. Wrong wavelength used
B. Insufficient chromophore concentration
C. Matrix interference
D. Stray light
D. Stray light
Which type of filter is best for measuring stray light?
A. Wratten
B. Didymium
C. Sharp cutoff
D. Neutral density
C. Sharp cutoff
Which of the following materials is best suited for verifying the wavelength calibration of a spectrophotometer?
A. Neutral density filters
B. Potassium dichromate solutions traceable to the
National Bureau of Standards reference
C. Wratten filters
D. Holmium oxide glass
D. Holmium oxide glass
Why do many optical systems in chemistry analyzers utilize a reference light path?
A. To increase the sensitivity of the measurement
B. To minimize error caused by source lamp fluctuation
C. To obviate the need for wavelength adjustment
D. To reduce stray light effects
B. To minimize error caused by source lamp fluctuation
Which component is required in a spectrophotometer in order to produce a spectral absorbance curve?
A. Multiple monochromators
B. A reference optical beam
C. Photodiode array
D. Laser light source
C. Photodiode array
The half-band width of a monochromator is defined by:
A. The range of wavelengths passed at 50% maximum transmittance
B. One-half the lowest wavelength of optical purity
C. The wavelength of peak transmittance
D. One-half the wavelength of peak absorbance
A. The range of wavelengths passed at 50% maximum transmittance
The reagent blank corrects for absorbance caused by:
A. The color of reagents
B. Sample turbidity
C. Bilirubin and hemolysis
D. All of these options
A. The color of reagents
A plasma sample is hemolyzed and turbid. What is required to perform a sample blank in order
to correct the measurement for the intrinsic absorbance of the sample when performing a
spectrophotometric assay?
A. Substitute deionized water for the sample
B. Dilute the sample 1:2 with a standard of known concentration
C. Substitute saline for the reagent
D. Use a larger volume of the sample
C. Substitute saline for the reagent
Which instrument requires a highly regulated DC power supply?
A. A spectrophotometer with a barrier layer cell
B. A colorimeter with multilayer interference filters
C. A spectrophotometer with a photomultiplier tube
D. A densitometer with a photodiode detector
C. A spectrophotometer with a photomultiplier tube
Which statement regarding reflectometry is true?
A. The relation between reflectance density and concentration is linear
B. Single-point calibration can be used to determine concentration
C. 100% reflectance is set with an opaque film called a white reference
D. The diode array is the photodetector of choice
C. 100% reflectance is set with an opaque film called a white reference
Bichromatic measurement of absorbance can correct for interfering substances if:
A. The contribution of the interferent to absorbance is the same at both wavelengths
B. Both wavelengths pass through the sample simultaneously
C. The side band is a harmonic of the primary wavelength
D. The chromogen has the same absorbance at both wavelengths
A. The contribution of the interferent to absorbance is the same at both wavelengths
Which instrument requires a primary andsecondary monochromator?
A. Spectrophotometer
B. Atomic absorption spectrophotometer
C. Fluorometer
D. Nephelometer
C. Fluorometer
Which of the following statements about fluorometry is accurate?
A. Fluorometry is less sensitive than spectrophotometry
B. Fluorometry is less specific than spectrophotometry
C. Unsaturated cyclic molecules are often fluorescent
D. Fluorescence is directly proportional to temperature
C. Unsaturated cyclic molecules are often fluorescent
Which of the following components is not needed in a chemiluminescent immunoassay analyzer?
A. Source lamp
B. Monochromator
C. Photodetector
D. Wash station
A. Source lamp
Which substance is used to generate the light signal in electrochemiluminescence?
A. Acridinium
B. Luminol
C. Dioxetane phosphate
D. Ruthenium
D. Ruthenium
Light scattering when the wavelength is greater than 10 times the particle diameter is described by:
A. Rayleigh’s law
B. The Beer–Lambert law
C. Mie’s law
D. The Rayleigh–Debye law
A. Rayleigh’s law
Which statement regarding nephelometry is true?
A. Nephelometry is less sensitive than absorption spectrophotometry
B. Nephelometry follows Beer’s law
C. The optical design is identical to a turbidimeter except that a HeNe laser light source is used
D. The detector response is directly proportional to concentration
D. The detector response is directly proportional to concentration
The purpose of the nebulizer in an atomic absorption spectrophotometer that uses a flame is to:
A. Convert ions to atoms
B. Cause ejection of an outer shell electron
C. Reduce evaporation of the sample
D. Burn off organic impurities
A. Convert ions to atoms
A flameless atomic absorption spectrophotometer dehydrates and atomizes a sample using:
A. A graphite capillary furnace
B. An electron gun
C. A thermoelectric semiconductor
D. A thermospray platform
A. A graphite capillary furnace
When measuring lead in whole blood using atomic absorption spectrophotometry, what reagent is
required to obtain the needed sensitivity and precision?
A. Lanthanum
B. Lithium
C. Triton X-100
D. Chloride
C. Triton X-100
Interference in atomic absorption spectrophotometry caused by differences in viscosity is called:
A. Absorption interference
B. Matrix effect
C. Ionization interference
D. Quenching
B. Matrix effect
All of the following are required when measuring magnesium by atomic absorption spectrophotometry except:
A. A hollow cathode lamp with a magnesium cathode
B. A chopper to prevent optical interference from magnesium emission
C. A monochromator to isolate the magnesium emission line at 285 nm
D. A 285-nm reference beam to correct for background absorption
D. A 285-nm reference beam to correct for background absorption
When measuring calcium by atomic absorption spectrophotometry, which is required?
A. An organic extraction reagent to deconjugate calcium from protein
B. An internal standard
C. A magnesium chelator
D. Lanthanum oxide to chelate phosphates
D. Lanthanum oxide to chelate phosphates
Ion selective analyzers using undiluted samples have what advantage over analyzers that use a
diluted sample?
A. Can measure over a wider range of concentration
B. Are not subject to pseudohyponatremia caused by high lipids
C. Do not require temperature equilibration
D. Require less maintenance
B. Are not subject to pseudohyponatremia caused
by high lipids
Select the equation describing the potential that develops at the surface of an ion-selective
electrode.
A. van Deemter equation
B. van Slyke equation
C. Nernst equation
D. Henderson–Hasselbalch equation
C. Nernst equation
The reference potential of a silver–silver chloride electrode is determined by the:
A. Concentration of the potassium chloride filling solution
B. Surface area of the electrode
C. Activity of total anion in the paste covering the electrode
D. The concentration of silver in the paste covering the electrode
A. Concentration of the potassium chloride filling
solution
The term RT/nF in the Nernst equation defines the:
A. Potential at the ion-selective membrane
B. Slope of the electrode
C. Decomposition potential
D. Isopotential point of the electrode
B. Slope of the electrode
The ion-selective membrane used to measure potassium is made of:
A. High-borosilicate glass membrane
B. Polyvinyl chloride dioctylphenyl phosphonate ion exchanger
C. Valinomycin gel
D. Calomel
C. Valinomycin gel
The response of a sodium electrode to a 10-fold increase in sodium concentration should be:
A. A 10-fold drop in potential
B. An increase in potential of approximately 60 mV
C. An increase in potential of approximately 10 mV
D. A decrease in potential of approximately 10 mV
B. An increase in potential of approximately 60 mV
Which of the electrodes below is a current-producing (amperometric) rather than a
voltage-producing (potentiometric) electrode?
A. Clark electrode
B. Severinghaus electrode
C. pH electrode
D. Ionized calcium electrode
A. Clark electrode
Which of the following would cause a “response” error from an ion-selective electrode for sodium
when measuring serum but not the calibrator?
A. Interference from other electrolytes
B. Protein coating the ion-selective membrane
C. An overrange in sodium concentration
D. Protein binding to sodium ions
B. Protein coating the ion-selective membrane
In polarography, the voltage needed to cause depolarization of the cathode is called the:
A. Half-wave potential
B. Isopotential point
C. Decomposition potential
D. Polarization potential
C. Decomposition potential
Persistent noise from an ion-selective electrode is most often caused by:
A. Contamination of sample
B. Blocked junction at the salt bridge
C. Overrange from high concentration
D. Improper calibration
B. Blocked junction at the salt bridge
Which element is reduced at the cathode of a Clark polarographic electrode?
A. Silver
B. Oxygen
C. Chloride
D. Potassium
B. Oxygen
Which of the following statements accurately characterizes the coulometric titration of chloride?
A. The indicator electrodes generate voltage
B. Constant current must be present across the generator electrodes
C. Silver ions are formed at the generator cathode
D. Chloride concentration is inversely proportional to titration time
B. Constant current must be present across the
generator electrodes
In the coulometric chloride titration:
A. Acetic acid in the titrating solution furnishes the counter ion for reduction
B. The endpoint is detected by amperometry
C. The titrating reagent contains a phosphate buffer to keep pH constant
D. Nitric acid (HNO3) is used to lower the solubility of AgCl
B. The endpoint is detected by amperometry
Which of the following compounds can interfere with the coulometric chloride assay?
A. Bromide
B. Ascorbate
C. Acetoacetate
D. Nitrate
A. Bromide
All of the following compounds contribute to the osmolality of plasma except:
A. Lipids
B. Creatinine
C. Drug metabolites
D. Glucose
A. Lipids
One mole per kilogram H2O of any solute will cause all of the following except:
A. Lower the freezing point by 1.86°C
B. Raise vapor pressure by 0.3 mm Hg
C. Raise the boiling point by 0.52°C
D. Raise osmotic pressure by 22.4 atm
B. Raise vapor pressure by 0.3 mm Hg
What component of a freezing point osmometer measures the sample temperature?
A. Thermistor
B. Thermocouple
C. Capacitor
D. Electrode
A. Thermistor
What type of measuring circuit is used in a freezing point osmometer?
A. Electrometer
B. Potentiometer
C. Wheatstone bridge
D. Thermal conductivity bridge
C. Wheatstone bridge
Which measurement principle is employed in a vapor pressure osmometer?
A. Seebeck
B. Peltier
C. Hayden
D. Darlington
A. Seebeck
The freezing point osmometer differs from the vapor pressure osmometer in that only the freezing
point osmometer:
A. Cools the sample
B. Is sensitive to ethanol
C. Requires a thermoelectric module
D. Requires calibration with aqueous standards
B. Is sensitive to ethanol
The method for measuring iron or lead by plating the metal and then oxidizing it is called:
A. Polarography
B. Coulometry
C. Anodic stripping voltometry
D. Amperometry
C. Anodic stripping voltometry
The term isocratic is used in high-performance liquid chromatography (HPLC) to mean the:
A. Mobile phase is at constant temperature
B. Stationary phase is equilibrated with the mobile phase
C. Mobile phase consists of a constant solvent composition
D. Flow rate of the mobile phase is regulated
C. Mobile phase consists of a constant solvent composition
The term reverse phase is used in HPLC to indicate that the mobile phase is:
A. More polar than the stationary phase
B. Liquid and the stationary phase is solid
C. Organic and the stationary phase is aqueous
D. A stronger solvent than the stationary phase
A. More polar than the stationary phase
What is the primary means of solute separation in HPLC using a C18 column?
A. Anion exchange
B. Size exclusion
C. Partitioning
D. Cation exchange
C. Partitioning
The most commonly used detector for clinical gas–liquid chromatography (GLC) is based upon:
A. Ultraviolet light absorbance at 254 nm
B. Flame ionization
C. Refractive index
D. Thermal conductance
B. Flame ionization
What type of detector is used in high-performance liquid chromatography with electrochemical
detection (HPLC–ECD)?
A. Calomel electrode
B. Conductivity electrode
C. Glassy carbon electrode
D. Polarographic electrode
C. Glassy carbon electrode
In gas chromatography, the elution order of volatiles is usually based upon the:
A. Boiling point
B. Molecular size
C. Carbon content
D. Polarity
A. Boiling point
Select the chemical that is used in most HPLC procedures to decrease solvent polarity.
A. Hexane
B. Nonane
C. Chloroform
D. Acetonitrile
D. Acetonitrile
In thin-layer chromatography (TLC), the distance the solute migrates divided by the distance the
solvent migrates is the:
A. tR
B. Kd
C. Rf
D. pK
C. Rf
Which reagent is used in thin-layer chromatography (TLC) to extract cocaine metabolites from urine?
A. Acid and sodium chloride
B. Alkali and organic solvent
C. Chloroform and sodium acetate
D. Neutral solution of ethyl acetate
B. Alkali and organic solvent
What is the purpose of an internal standard in HPLC and GC methods?
A. To compensate for variation in extraction and injection
B. To correct for background absorbance
C. To compensate for changes in flow rate
D. To correct for coelution of solutes
A. To compensate for variation in extraction and injection
What is the confirmatory method for measuring drugs of abuse?
A. HPLC
B. Enzyme-multiplied immunoassay technique (EMIT)
C. Gas chromatography with mass spectroscopy (GC-MS)
D. TLC
C. Gas chromatography with mass spectroscopy (GC-MS)
The fragments typically produced and analyzed in methods employing mass spectroscopy are
typically:
A. Of low molecular size ranging from 10–100 daltons
B. Cations caused by electron loss or proton attachment
C. Anions caused by bombarding the molecule with an electron source
D. Neutral species formed after excited molecules form a stable resonance structure
B. Cations caused by electron loss or proton attachment
What component is used in a GC-MS but not used in an LC-MS?
A. Electron source
B. Mass filter
C. Detector
D. Vacuum
A. Electron source
What process is most often used in LC-MS to introduce the sample into the mass filter?
A. Electrospray ionization
B. Chemical ionization
C. Electron impact ionization
D. Fast atom bombardment
A. Electrospray ionization
In mass spectroscopy, the term base peak typically refers to:
A. The peak with the lowest mass
B. The peak with the most abundance
C. A natural isotope of the molecular ion
D. The first peak to reach the mass detector
B. The peak with the most abundance
Which method is the most useful when screening for errors of amino and organic acid metabolism?
A. Two-dimensional thin-layer chromatography
B. Gas chromatography
C. Electrospray ionization tandem-mass spectroscopy
D. Inductively charged coupled-mass spectroscopy
C. Electrospray ionization tandem-mass spectroscopy
In tandem-mass spectroscopy, the first mass filter performs the same function as:
A. The ion source
B. The chromatography column
C. Extraction
D. The vacuum system
B. The chromatography column
SITUATION: A GC-MS analysis using nitrogen as the carrier gas shows an extensively noisy baseline.
A sample of the solvent used for the extraction procedure, ethyl acetate, was injected and showed
the same noise. Results of an Autotune test showed the appearance of a base peak at 16 with
two smaller peaks at 17 and 18. These results indicate:
A. The solvent is contaminated
B. The carrier gas is contaminated
C. There is electrical noise in the detector
D. The ion source is dirty
B. The carrier gas is contaminated
Why is vacuum necessary in the mass filter of a mass spectrometer?
A. Ionization does not occur at atmospheric pressure
B. It prevents collision between fragments
C. It removes electrons from the ion source
D. It prevents contamination
B. It prevents collision between fragments
What method is used to introduce the sample into a mass spectrometer for analysis of a trace element?
A. Electrospray ionization
B. Laser desorption
C. Inductively charged plasma (ICP) ionization
D. Direct injection
C. Inductively charged plasma (ICP) ionization
Which component is needed for a thermal cycler to amplify DNA?
A. Programmable heating and cooling unit
B. Vacuum chamber with zero head space
C. Sealed airtight constant-temperature chamber
D. Temperature-controlled ionization chamber
A. Programmable heating and cooling unit
In real-time PCR, what value is needed in order to etermine the threshold?
A. Background signal
B. Melt temperature
C. Maximum fluorescence
D. Threshold cycle
A. Background signal
Given the following real-time PCR amplification curve, what is the threshold cycle?
A. 15
B. 20
C. 25
D. 30
C. 25
In addition to velocity, what variable is also needed to calculate the relative centrifugal force
(g force) of a centrifuge?
A. Head radius
B. Angular velocity coefficient
C. Diameter of the centrifuge tube
D. Ambient temperature in degrees Centigrade
A. Head radius
Which of the following situations is likely to cause an error when weighing with an electronic
analytical balance?
A. Failure to keep the knife edge clean
B. Failure to close the doors of the balance before reading the weight
C. Oxidation on the surface of the substitution weights
D. Using the balance without allowing it to warm up for at least 10 minutes
B. Failure to close the doors of the balance before reading the weight
When calibrating a semiautomatic pipet that has a fixed delivery of 10.0 μL using a gravimetric
method, what should be the average weight of deionized water transferred?
A. 10.0 μg
B. 100.0 μg
C. 1.0 mg
D. 10.0 mg
D. 10.0 mg
Which of the following represents the Henderson–Hasselbalch equation as applied to blood pH?
A. pH = 6.1 + log HCO3–/PCO2
B. pH = 6.1 + log HCO3–/(0.03 × PCO2)
C. pH = 6.1 + log dCO2/HCO3–
D. pH = 6.1 + log (0.03 × PCO2)/HCO3–
B. pH = 6.1 + log HCO3–/(0.03 × PCO2)
What is the PO2 of calibration gas containing 20.0% O2, when the barometric pressure is 30 in.?
A. 60 mm Hg
B. 86 mm Hg
C. 143 mm Hg
D. 152 mm Hg
C. 143 mm Hg
What is the blood pH when the partial pressure of carbon dioxide (PCO2) is 60 mm Hg and the
bicarbonate concentration is 18 mmol/L?
A. 6.89
B. 7.00
C. 7.10
D. 7.30
C. 7.10
Which of the following best represents the reference (normal) range for arterial pH?
A. 7.35–7.45
B. 7.42–7.52
C. 7.38–7.68
D. 6.85–7.56
A. 7.35–7.45
What is the normal ratio of bicarbonate to dissolved carbon dioxide (HCO3–:dCO2) in arterial blood?
A. 1:10
B. 10:1
C. 20:1
D. 30:1
C. 20:1
What is the PCO2 if the dCO2 is 1.8 mmol/L?
A. 24 mm Hg
B. 35 mm Hg
C. 60 mm Hg
D. 72 mm Hg
C. 60 mm Hg
In the Henderson–Hasselbalch expression pH = 6.1 + log HCO3–/dCO2, the 6.1 represents:
A. The combined hydration and dissociation constants for CO2 in blood at 37°C
B. The solubility constant for CO2 gas
C. The dissociation constant of H2O
D. The ionization constant of sodium bicarbonate (NaHCO3)
A. The combined hydration and dissociation constants for CO2 in blood at 37°C
Which of the following contributes the most to the serum total CO2?
A. PCO2
B. dCO2
C. HCO3–
D. Carbonium ion
C. HCO3–
In addition to sodium bicarbonate, what other substance contributes most to the amount of base
in the blood?
A. Hemoglobin concentration
B. Dissolved O2 concentration
C. Inorganic phosphorus
D. Organic phosphate
A. Hemoglobin concentration
Which of the following effects results from exposure of a normal arterial blood sample to
room air?
A. PO2 increased PCO2 decreased pH increased
B. PO2 decreased PCO2 increased pH decreased
C. PO2 increased PCO2 decreased pH decreased
D. PO2 decreased PCO2 decreased pH decreased
A. PO2 increased PCO2 decreased pH increased
Which of the following formulas for O2 content is correct?
A. O2 content = %O2 saturation/100 × Hgb g/dL × 1.39 mL/g + (0.0031 × PO2)
B. O2 content = PO2 × 0.0306 mmol/L/mm
C. O2 content = O2 saturation × Hgb g/dL × 0.003 mL/g
D. O2 content = O2 capacity × 0.003 mL/g
A. O2 content = %O2 saturation/100 × Hgb g/dL × 1.39 mL/g + (0.0031 × PO2)
The normal difference between alveolar and arterial PO2 (PAO2–PaO2 difference) is:
A. 3 mm Hg
B. 10 mm Hg
C. 40 mm Hg
D. 50 mm Hg
B. 10 mm Hg
A decreased PAO2–PaO2 difference is found in:
A. A/V (arteriovenous) shunting
B. V/Q (ventilation/perfusion) inequality
C. Ventilation defects
D. All of these options
C. Ventilation defects
The determination of the oxygen saturation of hemoglobin is best accomplished by:
A. Polychromatic absorbance measurements of a whole-blood hemolysate
B. Near infrared transcutaneous absorbance measurement
C. Treatment of whole blood with alkaline dithionite prior to measuring absorbance
D. Calculation using PO2 and total hemoglobin by direct spectrophotometry
A. Polychromatic absorbance measurements of a whole-blood hemolysate
Correction of pH for a patient with a body temperature of 38°C would require:
A. Subtraction of 0.015
B. Subtraction of 0.01%
C. Addition of 0.020
D. Subtraction of 0.020
A. Subtraction of 0.015
Select the anticoagulant of choice for blood gas studies.
A. Sodium citrate 3.2%
B. Lithium heparin 100 U/mL blood
C. Sodium citrate 3.8%
D. Ammonium oxalate 5.0%
B. Lithium heparin 100 U/mL blood
What is the maximum recommended storage time and temperature for an arterial blood gas sample drawn in a plastic syringe?
Storage Time Temperature
a. 10 min 2°C–8°C
b. 20 min 2°C–8°C
c. 30 min 2°C–8°C
d. 30 min 22°C
d. 30 min 22°C
A patient’s blood gas results are as follows:
pH = 7.26
dCO2 = 2.0 mmol/L
HCO3– = 29 mmol/L
These results would be classified as:
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis
C. Respiratory acidosis
A patient’s blood gas results are:
pH = 7.50
PCO2 = 55 mm Hg
HCO3– = 40 mmol/L
These results indicate:
A. Respiratory acidosis
B. Metabolic alkalosis
C. Respiratory alkalosis
D. Metabolic acidosis
B. Metabolic alkalosis
Which set of results is consistent with uncompensated respiratory alkalosis?
A. pH 7.70 HCO3 30 mmol/L PCO2 25 mm Hg
B. pH 7.66 HCO3 22 mmol/L PCO2 20 mm Hg
C. pH 7.46 HCO3 38 mmol/L PCO2 55 mm Hg
D. pH 7.36 HCO3 22 mmol/L PCO2 38 mm Hg
B. pH 7.66 HCO3 22 mmol/L PCO2 20 mm Hg
Which of the following will shift the O2 dissociation curve to the left?
A. Anemia
B. Hyperthermia
C. Hypercapnia
D. Alkalosis
D. Alkalosis
In which circumstance will the reporting of calculated oxygen saturation of hemoglobin based on PO2, PCO2, pH, temperature, and hemoglobin be in error?
A. Carbon monoxide poisoning
B. Diabetic ketoacidosis
C. Patient receiving oxygen therapy
D. Assisted ventilation for respiratory failure
A. Carbon monoxide poisoning
Which would be consistent with partially compensated respiratory acidosis?
A. pH PCO2 Bicarbonate
increased increased increased
B. pH PCO2 Bicarbonate
increased decreased decreased
C. pH PCO2 Bicarbonate
decreased decreased decreased
D. pH PCO2 Bicarbonate
decreased increased increased
D. pH PCO2 Bicarbonate
decreased increased increased
Which condition results in metabolic acidosis with severe hypokalemia and chronic alkaline urine?
A. Diabetic ketoacidosis
B. Phenformin-induced acidosis
C. Renal tubular acidosis
D. Acidosis caused by starvation
C. Renal tubular acidosis
Which of the following mechanisms is responsible for metabolic acidosis?
A. Bicarbonate deficiency
B. Excessive retention of dissolved CO2
C. Accumulation of volatile acids
D. Hyperaldosteronism
A. Bicarbonate deficiency
Which of the following disorders is associated with lactate acidosis?
A. Diarrhea
B. Renal tubular acidosis
C. Hypoaldosteronism
D. Alcoholism
D. Alcoholism
Which of the following is the primary mechanism of compensation for metabolic acidosis?
A. Hyperventilation
B. Release of epinephrine
C. Aldosterone release
D. Bicarbonate excretion
A. Hyperventilation
The following conditions are all causes of alkalosis. Which condition is associated with respiratory
(rather than metabolic) alkalosis?
A. Anxiety
B. Hypovolemia
C. Hyperaldosteronism
D. Hypoparathyroidism
A. Anxiety
Which of the following conditions is associated with both metabolic and respiratory alkalosis?
A. Hyperchloremia
B. Hypernatremia
C. Hyperphosphatemia
D. Hypokalemia
D. Hypokalemia
Which of the following conditions is associated with both metabolic and respiratory alkalosis?
A. Hyperchloremia
B. Hypernatremia
C. Hyperphosphatemia
D. Hypokalemia
B. Hypernatremia
Which of the following conditions is classified as normochloremic acidosis?
A. Diabetic ketoacidosis
B. Chronic pulmonary obstruction
C. Uremic acidosis
D. Diarrhea
A. Diabetic ketoacidosis
Which PCO2 value would be seen in maximally compensated metabolic acidosis?
A. 15 mm Hg
B. 30 mm Hg
C. 40 mm Hg
D. 60 mm Hg
A. 15 mm Hg
A patient has the following arterial blood gas results:
pH = 7.56
PCO2 = 25 mm Hg
PO2 = 100 mm Hg
HCO3– = 22 mmol/L
These results are most likely the result of which condition?
A. Improper specimen collection
B. Prolonged storage
C. Hyperventilation
D. Hypokalemia
C. Hyperventilation
Why are three levels used for quality control of pH and blood gases?
A. Systematic errors can be detected earlier than with two controls
B. Analytical accuracy needs to be greater than for other analytes
C. High, normal, and low ranges must always be evaluated
D. A different level is needed for pH, PCO2, and PO2
A. Systematic errors can be detected earlier than with two controls
A single-point calibration is performed between each blood gas sample in order to:
A. Correct the electrode slope
B. Correct electrode and instrument drift
C. Compensate for temperature variance
D. Prevent contamination by the previous sample
B. Correct electrode and instrument drift
In which condition would hypochloremia be expected?
A. Respiratory alkalosis
B. Metabolic acidosis
C. Metabolic alkalosis
D. All of these options
C. Metabolic alkalosis
Given the following serum electrolyte data, determine the anion gap.
Na = 132 mmol/L
Cl = 90 mmol/L
HCO3– = 22 mmol/L
A. 12 mmol/L
B. 20 mmol/L
C. 64 mmol/L
D. Cannot be determined from the information provided
B. 20 mmol/L
Which of the following conditions will cause an increased anion gap?
A. Diarrhea
B. Hypoaldosteronism
C. Hyperkalemia
D. Renal failure
D. Renal failure
Alcoholism, liver failure, and hypoxia induce acidosis by causing:
A. Depletion of cellular NAD+
B. Increased excretion of bicarbonate
C. Increased retention of PCO2
D. Loss of carbonic anhydrase
A. Depletion of cellular NAD+
Which of the following is the primary mechanism causing respiratory alkalosis?
A. Hyperventilation
B. Deficient alveolar diffusion
C. Deficient pulmonary perfusion
D. Parasympathetic inhibition
A. Hyperventilation
Which condition can result in acidosis?
A. Cystic fibrosis
B. Vomiting
C. Hyperaldosteronism
D. Excessive O2 therapy
D. Excessive O2 therapy
Which of the following conditions is associated with an increase in ionized calcium (Cai) in the
blood?
A. Alkalosis
B. Hypoparathyroidism
C. Hyperalbuminemia
D. Malignancy
D. Malignancy
Which of the following laboratory results is consistent with primary hypoparathyroidism?
A. Low calcium; high inorganic phosphorus Pi
B. Low calcium; low Pi
C. High calcium; high Pi
D. High calcium; low Pi
A. Low calcium; high inorganic phosphorus Pi
Which of the following conditions is associated with hypophosphatemia?
A. Rickets
B. Multiple myeloma
C. Renal failure
D. Hypervitaminosis D
A. Rickets
Which of the following tests is consistently abnormal in osteoporosis?
A. High urinary calcium
B. High serum Pi
C. Low serum calcium
D. High urine or serum N-telopeptide of type 1 collagen
D. High urine or serum N-telopeptide of type 1 collagen
Which of the following is a marker for bone formation?
A. Osteocalcin
B. Tartrate resistant acid phosphatase (TRAP)
C. Urinary pyridinoline and deoxypyridinoline
D. Urinary C-telopeptide and N-telopeptide crosslinks (CTx and NTx)
A. Osteocalcin
What role do CTx and NTx play in the management of osteoporosis?
A. Increased urinary excretion is diagnostic of early stage disease
B. Increased levels indicate a low risk of developing osteoporosis
C. Decreased urinary excretion indicates a positive response to treatment
D. The rate of urinary excretion correlates with the stage of the disease
C. Decreased urinary excretion indicates a positive response to treatment
What role does vitamin D measurement play in the management of osteoporosis?
A. Vitamin D deficiency must be demonstrated to establish the diagnosis
B. Vitamin D is consistently elevated in osteoporosis
C. A normal vitamin D level rules out osteoporosis
D. Vitamin D deficiency is a risk factor for developing osteoporosis
D. Vitamin D deficiency is a risk factor for developing osteoporosis
Which statement best describes testing recommendations for vitamin D?
A. Vitamin D testing should be reserved only for those persons who demonstrate hypercalcemia
of an undetermined cause
B. Vitamin D testing should be specific for the 1,25(OH)D3 form
C. Testing should be for total vitamin D when screening for deficiency
D. Vitamin D testing should not be performed if the patient is receiving a vitamin D supplement
C. Testing should be for total vitamin D when screening for deficiency
The serum level of which of the following laboratory tests is decreased in both VDDR
and VDRR?
A. Vitamin D
B. Calcium
C. Pi
D. Parathyroid hormone
C. Pi
Which of the following is the most accurate measurement of Pi in serum?
A. Rate of unreduced phosphomolybdate formation at 340 nm
B. Measurement of phosphomolybdenum blue at 680 nm
C. Use of aminonaptholsulfonic acid to reduce phosphomolybdate
D. Formation of a complex with malachite green dye
A. Rate of unreduced phosphomolybdate formation at 340 nm
What is the percentage of serum calcium that is ionized (Cai)?
A. 30%
B. 45%
C. 60%
D. 80%
B. 45%
Which of the following conditions will cause erroneous Cai results? Assume that the samples
are collected and stored anaerobically, kept at 4°C until measurement, and stored for no
longer than 1 hour.
A. Slight hemolysis during venipuncture
B. Assay of whole blood collected in sodium oxalate
C. Analysis of serum in a barrier gel tube stored at 4°C until the clot has formed
D. Analysis of whole blood collected in sodium heparin, 20 U/mL (low-heparin tube)
B. Assay of whole blood collected in sodium oxalate
Which of the following conditions is associated with a low serum magnesium?
A. Addison’s disease
B. Hemolytic anemia
C. Hyperparathyroidism
D. Pancreatitis
D. Pancreatitis
When measuring calcium with the complexometric dye o-cresolphthalein
complexone, magnesium is kept from interfering by:
A. Using an alkaline pH
B. Adding 8-hydroxyquinoline
C. Measuring at 450 nm
D. Complexing to EDTA
B. Adding 8-hydroxyquinoline
Which electrolyte measurement is least affected by hemolysis?
A. Potassium
B. Calcium
C. Pi
D. Magnesium
B. Calcium
Which of the following conditions is associated with hypokalemia?
A. Addison’s disease
B. Hemolytic anemia
C. Digoxin intoxication
D. Alkalosis
D. Alkalosis
Which of the following conditions is most likely to produce an elevated plasma potassium?
A. Hypoparathyroidism
B. Cushing’s syndrome
C. Diarrhea
D. Digitalis overdose
D. Digitalis overdose
Which of the following values is the threshold critical value (alert or action level) for low plasma
potassium?
A. 1.5 mmol/L
B. 2.0 mmol/L
C. 2.5 mmol/L
D. 3.5 mmol/L
C. 2.5 mmol/L
Which electrolyte is least likely to be elevated in renal failure?
A. Potassium
B. Magnesium
C. Inorganic phosphorus
D. Sodium
D. Sodium
Which of the following is the primary mechanism for vasopressin (ADH) release?
A. Hypovolemia
B. Hyperosmolar plasma
C. Renin release
D. Reduced renal blood flow
B. Hyperosmolar plasma
Which of the following conditions is associated with hypernatremia?
A. Diabetes insipidus
B. Hypoaldosteronism
C. Burns
D. Diarrhea
A. Diabetes insipidus
Which of the following values is the threshold critical value (alert or action level) for high plasma
sodium?
A. 150 mmol/L
B. 160 mmol/L
C. 170 mmol/L
D. 180 mmol/L
B. 160 mmol/L
Which of the following conditions is associated with total body sodium excess?
A. Renal failure
B. Hyperthyroidism
C. Hypoparathyroidism
D. Diabetic ketoacidosis
A. Renal failure
Which of the following conditions is associated with hyponatremia?
A. Diuretic therapy
B. Cushing’s syndrome
C. Diabetes insipidus
D. Nephrotic syndrome
A. Diuretic therapy
Which of the following conditions involving electrolytes is described correctly?
A. Pseudohyponatremia occurs only when undiluted samples are measured
B. Potassium levels are slightly higher in heparinized plasma than in serum
C. Hypoalbuminemia causes low total calcium but does not affect Cai
D. Hypercalcemia may be induced by low serum magnesium
C. Hypoalbuminemia causes low total calcium but does not affect Cai
Which of the following laboratory results is usually associated with cystic fibrosis?
A. Sweat chloride greater than 60 mmol/L
B. Elevated serum sodium and chloride
C. Elevated fecal trypsin activity
D. Low glucose
A. Sweat chloride greater than 60 mmol/L
When performing a sweat chloride collection, which of the following steps will result in
analytical error?
A. Using unweighed gauze soaked in pilocarpine nitrate on the inner surface of the forearm to
stimulate sweating
B. Collecting more than 75 mg of sweat in 30 minutes
C. Leaving the preweighed gauze on the inside of the arm exposed to air during collection
D. Rinsing the collected sweat from the gauze pad using chloride titrating solution
C. Leaving the preweighed gauze on the inside of the arm exposed to air during collection
Which electrolyte level best correlates with plasma osmolality?
A. Sodium
B. Chloride
C. Bicarbonate
D. Calcium
A. Sodium
Which formula is most accurate in predicting plasma osmolality?
A. Na + 2(Cl) + BUN + glucose
B. 2(Na) + 2(Cl) + glucose + urea
C. 2(Na) + (glucose ÷ 18) + (BUN ÷ 2.8)
D. Na + Cl + K + HCO3
C. 2(Na) + (glucose ÷ 18) + (BUN ÷ 2.8)
Which of the following biochemical processes is promoted by insulin?
A. Glycogenolysis
B. Gluconeogenesis
C. Lipolysis
D. Uptake of glucose by cells
D. Uptake of glucose by cells
Which of the following hormones promotes hyperglycemia?
A. Calcitonin
B. Growth hormone
C. Aldosterone
D. Renin
B. Growth hormone
Which of the following is characteristic of type 1 diabetes mellitus?
A. Requires an oral glucose tolerance test for diagnosis
B. Is the most common form of diabetes mellitus
C. Usually occurs after age 40
D. Requires insulin replacement to prevent ketosis
D. Requires insulin replacement to prevent ketosis
Which of the following is characteristic of type 2 diabetes mellitus?
A. Insulin levels are consistently low
B. Most cases require a 3-hour oral glucose tolerance test to diagnose
C. Hyperglycemia is often controlled without insulin replacement
D. The condition is associated with unexplained weight loss
C. Hyperglycemia is often controlled without insulin replacement
Which of the following results falls within the diagnostic criteria for diabetes mellitus?
A. Fasting plasma glucose of 120 mg/dL
B. Two-hour postprandial plasma glucose of 160 mg/dL
C. Two-hour plasma glucose of 180 mg/dL following a 75 g oral glucose challenge
D. Random plasma glucose of 250 mg/dL and presence of symptoms
D. Random plasma glucose of 250 mg/dL and presence of symptoms
Select the most appropriate adult reference range for fasting blood glucose.
A. 40–105 mg/dL (2.22–5.82 mmol/L)
B. 60–140 mg/dL (3.33–7.77 mmol/L)
C. 65–99 mg/dL (3.61–5.50 mmol/L)
D. 75–150 mg/dL (4.16–8.32 mmol/L)
C. 65–99 mg/dL (3.61–5.50 mmol/L)
When preparing a patient for an oral glucose tolerance test (OGTT), which of the following
conditions will lead to erroneous results?
A. The patient remains ambulatory for 3 days prior to the test
B. Carbohydrate intake is restricted to below 150 g/day for 3 days prior to test
C. No food, coffee, tea, or smoking is allowed 8 hours before and during the test
D. Administration of 75 g of glucose is given to an adult patient following a 10–12-hour fast
B. Carbohydrate intake is restricted to below 150 g/day for 3 days prior to test
Which of the following 2-hour glucose challenge results would be classified as impaired glucose
tolerance (IGT)?
Two-hour serum glucose:
A. 130 mg/dL
B. 135 mg/dL
C. 150 mg/dL
D. 204 mg/dL
C. 150 mg/dL
Which statement regarding gestational diabetes mellitus (GDM) is correct?
A. Is diagnosed using the same oral glucose tolerance criteria as in nonpregnancy
B. Converts to diabetes mellitus after pregnancy in 60%–75% of cases
C. Presents no increased health risk to the fetus
D. Is defined as glucose intolerance originating during pregnancy
D. Is defined as glucose intolerance originating during pregnancy
Which of the following findings is characteristic of all forms of clinical hypoglycemia?
A. A fasting blood glucose value below 55 mg/dL
B. High fasting insulin levels
C. Neuroglycopenic symptoms at the time of low blood sugar
D. Decreased serum C peptide
C. Neuroglycopenic symptoms at the time of low blood sugar
Which statement regarding glycated (glycosylated)Hgb (G-Hgb) is true?
A. Has a sugar attached to the C-terminal end of the β chain
B. Is a highly reversible aminoglycan
C. Reflects the extent of glucose regulation in the 8- to 12-week interval prior to sampling
D. Will be abnormal within 4 days following an episode of hyperglycemia
C. Reflects the extent of glucose regulation in the 8- to 12-week interval prior to sampling
What is the American Diabetes Association recommended cutoff value for adequate control of
blood glucose in diabetics as measured by glycated hemoglobin?
A. 5%
B. 6.5%
C. 9.5%
D. 11%
B. 6.5%
Which statement regarding measurement of Hgb A1c is true?
A. Levels do not need to be done fasting
B. Both the labile and stable Hgb A1c fractions are measured
C. Samples should be measured within 2 hours of collection
D. The assay must be done by chromatography
A. Levels do not need to be done fasting
Which statement regarding measurement of Hgb A1c is true?
A. Levels do not need to be done fasting
B. Both the labile and stable Hgb A1c fractions are measured
C. Samples should be measured within 2 hours of collection
D. The assay must be done by chromatography
B. Both the labile and stable Hgb A1c fractions are measured
Evaluate the following chromatogram of a whole-blood hemolysate, and identify the cause
and best course of action.
A. Result is not reportable because hemoglobin F is present and interferes
B. The result is not reportable because hemoglobin C is present and interferes
C. The result is not reportable because labile hemoglobin A1c is present
D. The result is reportable; neither hemoglobin F or C interfere
D. The result is reportable; neither hemoglobin F or C interfere
Which statement best describes the use of the Hgb A1C test?
Peak Calibrated Retention Time Peak Area
% Area % Area
Alb 0.60 0.25 12500
F 0.50 0.50 11300
LA1c 0.75 0.70 15545
A1c 6.2 0.90 45112
P3 2.6 1.60 57489
Ao 48.0 1.8 994813
C 43.0 2.00 926745
A. Should be used for monitoring glucose control only
B. May be used for both diagnosis and monitoring
C. Should be used only to monitor persons with type 1 diabetes
D. May be used only to monitor persons with type 2 diabetes
B. May be used for both diagnosis and monitoring
According to American Diabetes Association criteria, which result is consistent with a diagnosis
of impaired fasting glucose?
A. 99 mg/dL
B. 117 mg/dL
C. 126 mg/dL
D. 135 mg/dL
B. 117 mg/dL
What is the recommended cutoff for the early detection of chronic kidney disease in diabetics
using the test for microalbuminuria?
A. >30 mg/g creatinine
B. >80 mg/g creatinine
C. >200 mg/g creatinine
D. >80 mg/L
A. >30 mg/g creatinine
In addition to measuring blood glucose, Hgb A1c, and microalbumin, which test should be done on
diabetic persons once per year?
A. Urine glucose
B. Urine ketones
C. Plasma fructosamines
D. Estimated glomerular filtration rate
D. Estimated glomerular filtration rate
Which testing situation is appropriate for the use of point-of-care whole-blood glucose methods?
A. Screening for type 2 diabetes mellitus
B. Diagnosis of diabetes mellitus
C. Monitoring of blood glucose control in type 1 and type 2 diabetics
D. Monitoring diabetics for hyperglycemic episodes only
C. Monitoring of blood glucose control in type 1 and type 2 diabetics
Which of the following is the reference method for measuring serum glucose?
A. Somogyi–Nelson
B. Hexokinase
C. Glucose oxidase
D. Glucose dehydrogenase
B. Hexokinase
Polarographic methods for glucose analysis are based upon which principle of measurement?
A. Nonenzymatic oxidation of glucose
B. The rate of O2 depletion
C. Chemiluminescence caused by formation of adenosine triphosphate (ATP)
D. The change in electrical potential as glucose is oxidized
B. The rate of O2 depletion
In addition to polarography, what other electrochemical method can be used to measure glucose in plasma?
A. Conductivity
B. Potentiometry
C. Anodic stripping voltammetry
D. Amperometry
D. Amperometry
Select the enzyme that is most specific for β-D-glucose.
A. Hexokinase
B. G-6-PD
C. Phosphohexisomerase
D. Glucose oxidase
D. Glucose oxidase
Select the coupling enzyme used in the hexokinase method for glucose.
A. Glucose-6-phosphate dehydrogenase
B. Peroxidase
C. Glucose dehydrogenase
D. Glucose-6-phosphatase
A. Glucose-6-phosphate dehydrogenase
Select the coupling enzyme used in the hexokinase method for glucose.
A. Glucose-6-phosphate dehydrogenase
B. Peroxidase
C. Glucose dehydrogenase
D. Glucose-6-phosphatase
C. Glucose dehydrogenase
Which of the following is a potential source of error in the hexokinase method?
A. Galactosemia
B. Hemolysis
C. Sample collected in fluoride
D. Ascorbic acid
B. Hemolysis
Which statement about glucose in cerebrospinal fluid (CSF) is correct?
A. Levels below 40 mg/dL occur in septic meningitis, cancer, and multiple sclerosis
B. CSF glucose is normally the same as the plasma glucose level
C. Hyperglycorrhachia is caused by dehydration
D. In some clinical conditions, the CSF glucose can be greater than the plasma glucose
A. Levels below 40 mg/dL occur in septic meningitis, cancer, and multiple sclerosis
In peroxidase-coupled glucose methods, which reagent complexes with the chromogen?
A. Nitroprusside
B. Phenol
C. Tartrate
D. Hydroxide
B. Phenol
Point-of-care-tests (POCTs) for whole-blood glucose monitoring are based mainly on the use of:
A. Glucose oxidase as the enzyme
B. Amperometric detection
C. Immunochromatography
D. Peroxidase coupling reactions
B. Amperometric detection
What effect does hematocrit have on POCT tests for whole-blood glucose monitoring?
A. Low hematocrit decreases glucose readings on all devices
B. High hematocrit raises glucose readings on all devices
C. The effect is variable and dependent on the enzyme/coenzyme system
D. Low hematocrit raises readings and high hematocrit lowers readings unless corrected
D. Low hematocrit raises readings and high hematocrit lowers readings unless corrected
Which of the following is classified as a mucopolysaccharide storage disease?
A. Pompe’s disease
B. von Gierke disease
C. Hers’ disease
D. Hurler’s syndrome
D. Hurler’s syndrome
Identify the enzyme deficiency responsible for type 1 glycogen storage disease (von Gierke’s disease).
A. Glucose-6-phosphatase
B. Glycogen phosphorylase
C. Glycogen synthetase
D. β-Glucosidase
A. Glucose-6-phosphatase
Which of the following abnormal laboratory results is found in von Gierke’s disease?
A. Hyperglycemia
B. Increased glucose response to epinephrine administration
C. Metabolic alkalosis
D. Hyperlipidemia
D. Hyperlipidemia
The D-xylose absorption test is used for the differential diagnosis of which two diseases?
A. Pancreatic insufficiency from malabsorption
B. Primary from secondary disorders of glycogen synthesis
C. Type 1 and type 2 diabetes mellitus
D. Generalized from specific carbohydrate intolerance
A. Pancreatic insufficiency from malabsorption
Which of the following statements aboutcarbohydrate intolerance is true?
A. Galactosemia results from deficiency of galactose-1-phosphate (galactose-1-PO4) uridine diphosphate transferase
B. Galactosemia results in a positive glucose oxidase test for glucose in urine
C. Urinary galactose is seen in both galactosemia and lactase deficiency
D. A galactose tolerance test is used to confirm a diagnosis of galactosemia
A. Galactosemia results from deficiency of galactose-1-phosphate (galactose-1-PO4) uridine diphosphate transferase
Which of the following statements regarding iron metabolism is correct?
A. Iron absorption is decreased by alcohol ingestion
B. Normally, 40%–50% of ingested iron is absorbed
C. The daily requirement is higher for pregnant and menstruating women
D. Absorption increases with the amount of iron in the body stores
C. The daily requirement is higher for pregnant and menstruating women
Which of the following statements regarding iron metabolism is correct?
A. Iron absorption is decreased by alcohol ingestion
B. Normally, 40%–50% of ingested iron is absorbed
C. The daily requirement is higher for pregnant and menstruating women
D. Absorption increases with the amount of iron in the body stores
B. Normally, 40%–50% of ingested iron is absorbed
Which of the following is associated with low serum iron and high total iron-binding capacity (TIBC)?
A. Iron deficiency anemia
B. Hepatitis
C. Nephrosis
D. Noniron deficiency anemias
A. Iron deficiency anemia
Which condition is associated with the lowest percent saturation of transferrin?
A. Hemochromatosis
B. Anemia of chronic infection
C. Iron deficiency anemia
D. Noniron deficiency anemia
C. Iron deficiency anemia
Which condition is most often associated with a high serum iron level?
A. Nephrosis
B. Chronic infection or inflammation
C. Polycythemia vera
D. Noniron deficiency anemias
D. Noniron deficiency anemias
Which of the following is likely to occur first in iron deficiency anemia?
A. Decreased serum iron
B. Increased TIBC
C. Decreased serum ferritin
D. Increased transferrin
C. Decreased serum ferritin
Which formula provides the best estimate of serum TIBC?
A. Serum transferrin in mg/dL × 0.70 = TIBC (μg/dL)
B. Serum transferrin in mg/dL × 1.43 = TIBC (μg/dL)
C. Serum iron (μg/dL)/1.2 + 0.06 = TIBC (μg/dL)
D. Serum Fe (μg/dL) × 1.25 = TIBC (μg/dL)
B. Serum transferrin in mg/dL × 1.43 = TIBC (μg/dL)
Which statement regarding the diagnosis of iron deficiency is correct?
A. Serum iron levels are always higher at night than during the day
B. Serum iron levels begin to fall before the body stores become depleted
C. A normal level of serum ferritin rules out iron deficiency
D. A low serum ferritin is diagnostic of iron deficiency
D. A low serum ferritin is diagnostic of iron deficiency
Which statement about iron methods is true?
A. Interference from Hgb can be corrected by a serum blank
B. Colorimetric methods measure binding of Fe2+ to a ligand such as ferrozine
C. Atomic absorption is the method of choice for measurement of serum iron
D. Serum iron can be measured by potentiometry
B. Colorimetric methods measure binding of Fe2+ to a ligand such as ferrozine
Which of the following statements regarding the TIBC assay is correct?
A. All TIBC methods require addition of excess iron to saturate transferrin
B. All methods require the removal of unbound iron
C. Measurement of TIBC is specific for transferrin-bound iron
D. The chromogen used must be different from the one used for measuring serum iron
A. All TIBC methods require addition of excess iron to saturate transferrin
Which of the following statements regarding the metabolism of bilirubin is true?
A. It is formed by hydrolysis of the α methene bridge of urobilinogen
B. It is reduced to biliverdin prior to excretion
C. It is a by-product of porphyrin production
D. It is produced from the destruction of RBCs
D. It is produced from the destruction of RBCs
Bilirubin is transported from reticuloendothelial cells to the liver by:
A. Albumin
B. Bilirubin-binding globulin
C. Haptoglobin
D. Transferrin
A. Albumin
In the liver, bilirubin is conjugated by addition of:
A. Vinyl groups
B. Methyl groups
C. Hydroxyl groups
D. Glucuronyl groups
D. Glucuronyl groups
Which enzyme is responsible for the conjugation of bilirubin?
A. β-Glucuronidase
B. UDP-glucuronyl transferase
C. Bilirubin oxidase
D. Biliverdin reductase
B. UDP-glucuronyl transferase
The term δ-bilirubin refers to:
A. Water-soluble bilirubin
B. Free unconjugated bilirubin
C. Bilirubin tightly bound to albumin
D. Direct-reacting bilirubin
C. Bilirubin tightly bound to albumin
Which of the following processes is part of the normal metabolism of bilirubin?
A. Both conjugated and unconjugated bilirubin are excreted into the bile
B. Methene bridges of bilirubin are reduced by intestinal bacteria forming urobilinogens
C. Most of the bilirubin delivered into the intestine is reabsorbed
D. Bilirubin and urobilinogen reabsorbed from the intestine are mainly excreted by the kidneys
B. Methene bridges of bilirubin are reduced by intestinal bacteria forming urobilinogens
Which of the following is a characteristic of conjugated bilirubin?
A. It is water soluble
B. It reacts more slowly than unconjugated bilirubin
C. It is more stable than unconjugated bilirubin
D. It has the same absorbance properties as unconjugated bilirubin
A. It is water soluble
Which of the following statements regarding urobilinogen is true?
A. It is formed in the intestines by bacterial reduction of bilirubin
B. It consists of a single water-soluble bile pigment
C. It is measured by its reaction with p-aminosalicylate
D. In hemolytic anemia, it is decreased in urine and feces
A. It is formed in the intestines by bacterial reduction of bilirubin
Which statement regarding bilirubin metabolism is true?
A. Bilirubin undergoes rapid photo-oxidation when exposed to daylight
B. Bilirubin excretion is inhibited by barbiturates
C. Bilirubin excretion is increased by chlorpromazine
D. Bilirubin is excreted only as the diglucuronide
A. Bilirubin undergoes rapid photo-oxidation when exposed to daylight
Which condition is caused by deficient secretion of bilirubin into the bile canaliculi?
A. Gilbert’s disease
B. Neonatal hyperbilirubinemia
C. Dubin–Johnson syndrome
D. Crigler–Najjar syndrome
C. Dubin–Johnson syndrome
In hepatitis, the rise in serum conjugated bilirubin can be caused by:
A. Secondary renal insufficiency
B. Failure of the enterohepatic circulation
C. Enzymatic conversion of urobilinogen to bilirubin
D. Extrahepatic conjugation
B. Failure of the enterohepatic circulation
Which of the following is a characteristic of obstructive jaundice?
A. The ratio of direct to total bilirubin is greater than 1:2
B. Conjugated bilirubin is elevated, but unconjugated bilirubin is normal
C. Urinary urobilinogen is increased
D. Urinary bilirubin is normal
A. The ratio of direct to total bilirubin is greater than 1:2
Which of the following would cause an increase in only the unconjugated bilirubin?
A. Hemolytic anemia
B. Obstructive jaundice
C. Hepatitis
D. Hepatic cirrhosis
A. Hemolytic anemia
Which form of hyperbilirubinemia is caused by an inherited absence of UDP-glucuronyl transferase?
A. Gilbert’s syndrome
B. Rotor syndrome
C. Crigler–Najjar syndrome
D. Dubin–Johnson syndrome
C. Crigler–Najjar syndrome
Which statement regarding total and direct bilirubin levels is true?
A. Total bilirubin level is a less sensitive and specific marker of liver disease than the direct level
B. Direct bilirubin exceeds 3.5 mg/dL in most cases of hemolytic anemia
C. Direct bilirubin is normal in cholestatic liver disease
D. The ratio of direct to total bilirubin exceeds 0.40 in hemolytic anemia
A. Total bilirubin level is a less sensitive and specific marker of liver
Which statement best characterizes serum bilirubin levels in the first week following delivery?
A. Serum bilirubin 24 hours after delivery should not exceed the upper reference limit for adults
B. Jaundice is usually first seen 48–72 hours postpartum in neonatal hyperbilirubinemia
C. Serum bilirubin above 5.0 mg/dL occurring 2–5 days after delivery indicates hemolytic or
hepatic disease
D. Conjugated bilirubin accounts for about 50% of the total bilirubin in neonates
B. Jaundice is usually first seen 48–72 hours postpartum in neonatal hyperbilirubinemia
Which form of jaundice occurs within days of delivery and usually lasts 1–3 weeks, but is not
due to normal neonatal hyperbilirubinemia or hemolytic disease of the newborn?
A. Gilbert syndrome
B. Lucey –Driscoll syndrome
C. Rotor syndrome
D. Dubin–Johnson syndrome
B. Lucey –Driscoll syndrome
A lab measures total bilirubin by the Jendrassik–Grof bilirubin method with sample blanking. What would be the effect of moderate hemolysis on the test result?
A. Falsely increased due to optical interference
B. Falsely increased due to release of bilirubin from RBCs
C. Falsely low due to inhibition of the diazo reaction by hemoglobin
D. No effect due to correction of positive interference by sample blanking
C. Falsely low due to inhibition of the diazo reaction by hemoglobin
Which reagent is used in the Jendrassik–Grof method to solubilize unconjugated bilirubin?
A. 50% methanol
B. N-butanol
C. Caffeine
D. Acetic acid
C. Caffeine
Which statement about colorimetric bilirubin methods is true?
A. Direct bilirubin must react with diazo reagent under alkaline conditions
B. Most methods are based upon reaction with diazotized sulfanilic acid
C. Ascorbic acid can be used to eliminate interference caused by Hgb
D. The color of the azobilirubin product is independent of pH
B. Most methods are based upon reaction with diazotized sulfanilic acid
Which statement regarding the measurement of bilirubin by the Jendrassik–Grof method is
correct?
A. The same diluent is used for both total and direct assays to minimize differences in reactivity
B. Positive interference by Hgb is prevented by the addition of HCl after the diazo reaction
C. The color of the azobilirubin product is intensified by the addition of ascorbic acid
D. Fehling’s reagent is added after the diazo reaction to reduce optical interference by hemoglobin
D. Fehling’s reagent is added after the diazo reaction to reduce optical interference by hemoglobin
A neonatal bilirubin assay performed at the nursery by bichromatic direct spectrophotometry
is 4.0 mg/dL. Four hours later, a second sample assayed for total bilirubin by the Jendrassik–Grof
method gives a result of 3.0 mg/dL. Both samples are reported to be hemolyzed. What is the most
likely explanation of these results?
A. Hgb interference in the second assay
B. δ-Bilirubin contributing to the result of the first assay
C. Falsely high results from the first assay caused by direct bilirubin
D. Physiological variation owing to premature hepatic microsomal enzymes
A. Hgb interference in the second assay
In the enzymatic assay of bilirubin, how is measurement of both total and direct bilirubin
accomplished?
A. Using different pH for total and direct assays
B. Using UDP glucuronyl transferase and bilirubin reductase
C. Using different polarity modifiers
D. Measuring the rate of absorbance decrease at different time intervals
A. Using different pH for total and direct assays
What is the principle of the transcutaneous bilirubin assay?
A. Conductivity
B. Amperometric inhibition
C. Multiwavelength reflectance photometry
D. Infrared spectroscopy
C. Multiwavelength reflectance photometry
How many grams of sodium hydroxide (NaOH) are required to prepare 150.0 mL of a 5.0% w/v
solution?
A. 1.5 g
B. 4.0 g
C. 7.5 g
D. 15.0 g
C. 7.5 g
How many milliliters of glacial acetic acid are needed to prepare 2.0 L of 10.0% v/v acetic acid?
A. 10.0 mL
B. 20.0 mL
C. 100.0 mL
D. 200.0 mL
D. 200.0 mL
A biuret reagent requires preparation of a stock solution containing 9.6 g of copper II sulfate (CuSO4) per liter. How many grams of CuSO4 • 5H2O are needed to prepare 1.0 L of the stock solution?
Atomic weights:
H = 1.0;
Cu = 63.6;
O = 16.0;
S = 32.1
A. 5.4 g
B. 6.1 g
C. 15.0 g
D. 17.0 g
C. 15.0 g
How many milliliters of HNO3 (purity 68.0%, specific gravity 1.42) are needed to prepare 1.0 L
of a 2.0 N solution?
Atomic weights: H = 1.0; N = 14.0; O = 16.0
A. 89.5 mL
B. 126.0 mL
C. 130.5 mL
D. 180.0 mL
C. 130.5 mL
Convert 10.0 mg/dL calcium (atomic weight = 40.1) to International System of Units (SI).
A. 0.25
B. 0.40
C. 2.5
D. 0.4
C. 2.5
Convert 2.0 mEq/L magnesium (atomic weight = 24.3) to milligrams per deciliter.
A. 0.8 mg/dL
B. 1.2 mg/dL
C. 2.4 mg/dL
D. 4.9 mg/dL
C. 2.4 mg/dL
How many milliliters of a 2,000.0 mg/dL glucose stock solution are needed to prepare 100.0 mL of a 150.0 mg/dL glucose working standard?
A. 1.5 mL
B. 7.5 mL
C. 15.0 mL
D. 25.0 mL
B. 7.5 mL
What is the pH of a solution of HNO3, if the hydrogen ion concentration is 2.5 × 10–2 M?
A. 1.0
B. 1.6
C. 2.5
D. 2.8
B. 1.6
Calculate the pH of a solution of 1.5 × 10–5 M NH4OH.
A. 4.2
B. 7.2
C. 9.2
D. 11.2
C. 9.2
How many significant figures should be reported when the pH of a 0.060 M solution of nitric acid
is calculated?
A. 1
B. 2
C. 3
D. 4
B. 2
What is the pH of a 0.05 M solution of acetic acid? Ka = 1.75 × 10–5, pKa = 4.76
A. 1.7
B. 3.0
C. 4.3
D. 4.6
B. 3.0
What is the pH of a buffer containing 40.0 mmol/L NaHC2O4 and 4.0 mmol/L H2C2O4? (pKa = 1.25)
A. 1.35
B. 2.25
C. 5.75
D. 6.12
B. 2.25
A solvent needed for HPLC requires a 20.0 mmol/L phosphoric acid buffer, pH 3.50, made by mixing KH2PO4 and H3PO4. How many grams of KH2PO4 are required to make 1.0 L of this
buffer? Formula weights: KH2PO4 = 136.1; H3PO4 = 98.0; pKa H3PO4 = 2.12
A. 1.96 g
B. 2.61 g
C. 2.72 g
D. 19.2 g
B. 2.61 g
A procedure for cholesterol is calibrated with a serum-based cholesterol standard that was
determined by the Abell–Kendall method to be 200.0 mg/dL. Assuming the same volume of sample and reagent are used, calculate the cholesterol concentration in the patient’s sample from the following results.
Standard Concentration = 200 mg/dL
Absorbance of Reagent Blank = 0.00
Absorbance of Standard = 0.860
Absorbance of Patient Serum = 0.740
A. 123 mg/dL
B. 172 mg/dL
C. 232 mg/dL
D. 314 mg/dL
B. 172 mg/dL
A glycerol kinase method for triglyceride calls for a serum blank in which normal saline is substituted for lipase in order to measure endogenous glycerol. Given the following results, and assuming the same volume of sample and reagent are used for each test, calculate the triglyceride concentration in the patient’s sample.
A. 119 mg/dL
B. 131 mg/dL
C. 156 mg/dL
D. 180 mg/dL
B. 131 mg/dL
A procedure for aspartate aminotransferase (AST) is performed manually because of a repeating error code for nonlinearity obtained on the laboratory’s automated chemistry analyzer; 0.05 mL of serum and 1.0 mL of substrate are used. The reaction rate is measured at 30°C at 340 nm using a 1.0 cM light path, and the delta absorbance (-ΔA) per minute is determined to be 0.382. Based upon a molar absorptivity coefficient for NADH at 340 nm of 6.22 X 103 M–1 cM–1 L–1, calculate the enzyme activity in international units (IUs) per liter.
A. 26 IU/L
B. 326 IU/L
C. 1228 IU/L
D. 1290 IU/L
D. 1290 IU/L
When referring to quality control (QC) results, what parameter usually determines the acceptable
range?
A. The 95% confidence interval for the mean
B. The range that includes 50% of the results
C. The central 68% of results
D. The range encompassed by ±2.5 standard deviations
A. The 95% confidence interval for the mean
Which of the following quality control (QC) rules would be broken 1 out of 20 times by chance alone?
A. 12s
B. 22s
C. 13s
D. 14s
A. 12s
Which of the following conditions is cause for rejecting an analytical run?
A. Two consecutive controls greater than 2 s above or below the mean
B. Three consecutive controls greater than 1 s above the mean
C. Four controls steadily increasing in value but less than ±1 s from the mean
D. One control above +1 s and the other below –1 s from the mean
A. Two consecutive controls greater than 2 s above or below the mean
One of two controls within a run is above +2s and the other control is below –2s from the mean.
What do these results indicate?
A. Poor precision has led to random error (RE)
B. A systematic error (SE) is present
C. Proportional error is present
D. QC material is contaminated
A. Poor precision has led to random error (RE)
Two consecutive controls are both beyond –2s from the mean. How frequently would this occur
on the basis of chance alone?
A. 1:100
B. 5:100
C. 1:400
D. 1:1,600
D. 1:1,600
The term R4S means that:
A. Four consecutive controls are greater than ±1
standard deviation from the mean
B. Two controls in the same run are greater than
4s units apart
C. Two consecutive controls in the same run are
each greater than ±4s from the mean
D. There is a shift above the mean for four
consecutive controls
B. Two controls in the same run are greater than
4s units apart
A trend in QC results is most likely caused by:
A. Deterioration of the reagent
B. Miscalibration of the instrument
C. Improper dilution of standards
D. Electronic noise
A. Deterioration of the reagent
