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Clinical Chemistry Practicum > Quiz Questions > Flashcards

Quiz Questions Flashcards

1
Q

What is the maximum recommended time from specimen collection that plasma or serum can sit unspun?

A

2 hours after collection

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2
Q

Which of the following is correct regarding CSF handling and processing if only one tube of specimen is collected?

A

Microbiology will be first to handle & process this sample

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3
Q

Which of the following POCT categories is subject to the lowest level of regulation?

A

Waived tests

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4
Q

When using dry ice for transportation of frozen or refrigerated specimens, why should the container be vented?

A

To prevent build-up of carbon dioxide under pressure

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5
Q

What is the most critical aspect of blood culture collection?

A

Skin antisepsis

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6
Q

Why are EDTA specimens obtained before other specimens when collected by skin puncture?

A

To minimize effects of platelet clumping

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7
Q

How does heparin prevent blood from clotting?

A

By inhibiting thrombin

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8
Q

What is the change prolonged tourniquet application may cause in blood composition?

A

Hemoconcentration

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9
Q

Which instance may lead you to suspect that you have accidentally punctured an artery during a venipuncture?

A

The blood pulses into the tube

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10
Q

What is the maximum time that a tourniquet should be applied?

A

1 minute

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11
Q

Which of the following is the greatest source of error in POCT?

A

Pre-analytical errors

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12
Q

What is the purpose of reverse isolation?

A

To protect susceptible patients from outside contamination

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13
Q

A missing blood sample is found in the phlebotomist’s tray 4 hours after collection. Which tests would be most affected by this delay in centrifugation?

A

Glucose, electrolytes

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14
Q

Which of the following crystals may be present in a urine with a pH of 7.5?

A

Triple phosphate

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15
Q

What is the most common source of false negative results for Glucose reagent strip testing on urines?

A

Improperly preserved urine

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16
Q

Which pathological condition should be considered when large numbers of calcium oxalate crystals are seen in the urine?

A

Ethylene glycol ingestion (anti-freeze)

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17
Q

Which of the following casts is most associated with tubular obstruction and prolonged urine stasis?

A

Waxy casts

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18
Q

The protein dip stick test is based on “protein error” of an indicators. What does this mean?

A

At a specified pH the indicator will change color in the presence of protein

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19
Q

Which specific gravity is most plausible in the urine of a patient with untreated diabetes insipidus?

A

1.001 - 1.005

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20
Q

Urine has tested positive for blood using a reagent strip but microscopic examination shows no red blood cells. How would one account for this discrepancy?

A

Urine is contaminated with strong oxidizing agents such as soaps or detergents

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21
Q

Which of these casts is most associated with glomerulonephritis?

A

RBC casts

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22
Q

When processing urine specimens for analysis, which of the actions can cause falsely high counts of microscopic urine sediment?

A

Centrifuging a larger volume of urine than the procedure indicates

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23
Q

Which of the following describes the clinical significance of testing urine specific gravity?

A

Detects loss of renal tubular concentrating ability

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24
Q

A urine specimen from a patient with a hemolytic transfusion reaction would be expected to show which of the following?

A

Positive for urobilinogen; negative for bilirubin

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25
Q

What factor enhances formation of casts in the distal and collecting tubules of the kidney?

A

Increased solute and protein excretion

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26
Q

What is the Creatinine Clearance Formula?

A

CC = U(cr) x U(vol) x 1.73
S(cr) t BSA

CC= urine (creatine) in L/serum CR x Urine/Time (Hrx60) x 1.73/BSA

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27
Q

Which of the following situations could create a falsely high urine pH?

A

Storage of urine at room temperature for 5 hours

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28
Q

In hypertonic urine, how do red blood cells predominately appear under the microscope?

A

Crenated cells

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29
Q

It is important to blot excess urine off the urine dipstick after dipping. Otherwise “run-over” will occur when the acid buffer from the reagent in the protein area runs into the pH area. What effect will run-over produce?

A

False lowering of the pH reading, especially in alkaline urine

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30
Q

Which of the following statements is true about glucose testing by reagent strips?

A

Glucose oxidase and peroxidase are impregnated onto the reagent strip

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31
Q

Which of the following needs to be considered when a urine specific gravity result is less than 1.000?

A

This result is not plausible

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32
Q

What term is used to describe white cells which expand in dilute or hypotonic urine, and may have granules that demonstrate Brownian motion?

A

Glitter Cells

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33
Q

Which of the following statements is correct with regards to the calibration of pipettes?

A

Pipette calibration is performed to verify accuracy & precision of the device

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34
Q

Which term best describes procedures that remove all contamination by killing microorganisms and their spores?

A

Sterilization

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35
Q

Which of the following must be stable in the reagent for accurate measurements of lactate dehydrogenase?

A

NAD/NADH

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36
Q

A mole of NaCl is added to a kilogram of water. Which of the following changes occurs in the colligative properties of this solution?

A

osmotic pressure is increased and freezing point is decreased

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37
Q

Which of the following most affects measurement of freezing point depression?

A

Number of solutes and dissociation of those solutes

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38
Q

Which of the following ketone bodies is predominantly tested in urine?

A

Acetoacetate

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39
Q

Which one of the following results may indicate primary hyperthyroidism?

A

↑free T3

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40
Q

Which of the following enzyme combinations is useful as an indication of obstructive jaundice?

A

GGT, alkaline phosphatase

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41
Q

Which statement best characterizes Type I diabetes?

A

High glucose levels lead to ketoacidosis

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42
Q

Why is the glucose oxidase method highly specific?

A

It uses enzymatic reagents

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43
Q

Which of these statements is true about anti-diuretic hormone (ADH)?

A

It will be secreted if a person is dehydrated

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44
Q

A patient has a glucose result of 6.1 mmol/L with an elevated hemoglobin A1C and normal CBC. What would explain these results?

A

Patient’s glucose was well managed for the day of collection but long term management was poor

45
Q

Which lipid profile below is associated with coronary heart disease?

A

Decreased HDL, increased LDL and triglycerides

46
Q

Which of the following tests are most useful in the diagnosis of acute pancreatitis?

A

Lipase

47
Q

In a competitive immunoassay done to measure a drug level, which of the following is constant?

A

Labelled antigen

48
Q

What is the number of amplified pieces of DNA after five cycles of PCR?

A

32

2 to the power of cycles

49
Q

In a PCR, which of these functions are dNTP’s involved in?

A

Extension

50
Q

Which statement regarding sandwich ELISA is correct?

A

Antibody is labelled with enzyme

51
Q

What is the most common method for measuring therapeutic drug levels?

A

Immunoassay

52
Q

Which of the following is correct in regards to the majority of therapeutic drug analysis?

A

Most methods will analyze the free and bound drug combined

53
Q

What is the principle of measurement by chemiluminescence immunoassay?

A

Amount of light emission caused by products of a specific chemical reaction

54
Q

Most toxic reactions of drug overdoses lead to metabolic acidosis. Which of the following creates an initial respiratory alkalosis?

A

Salicylate

55
Q

What is the most common confirmatory testing method for drugs of abuse?

A

Gas chromatography/mass spectrometry

56
Q

What effect does antigen excess have during an immunoassay?

A

Falsely low results

57
Q

What is the appropriate time for the collection of trough drug levels?

A

Just before dosage is given

58
Q

Which of the following reagents is excluded from a PCR reaction?

A

Polyethylene glycol

59
Q

What statement is correct in regards to FPIA?

A

Uses an antigen labeled with a fluorescing molecule

60
Q

In TDM pharmacokinetics, which of the following best describes steady state?

A

Condition in which drug input and drug output are equal

61
Q

A patient is exhibiting symptoms of drug toxicity but the lab results show the drug to be in therapeutic range. What is the most likely explanation to this issue?

A

The patient’s disease state produced an altered drug absorption and distribution

62
Q

Which statement is true with regards to metabolism and elimination of the majority of therapeutic drugs?

A

Most drugs are metabolized by the liver and eliminated by the kidneys

63
Q

Which statement best describes immunofixation electrophoresis (IFE)?

A

Proteins are separated by electrophoresis followed by overlay of monospecific anti-immunoglobulins

64
Q

In steric exclusion chromatography, molecules are separated on the basis of size and shape. Which statement is true?

A

Column is packed with a porous material

65
Q

Which of the following gas chromatography detectors is the most sensitive and stable?

A

Flame-ionization

65
Q

Which one of the following is most likely to be increased in an acute infection?

A

IgM

66
Q

How can denaturation of serum proteins be minimized during electrophoresis?

A

Maintaining an optimal current

67
Q

Which chromatography system uses silica gel on a piece of glass and a mobile phase of liquid?

A

Thin-layer

68
Q

Unexpected results were obtained upon performing serum protein electrophoresis. Protein bands look shorter and brighter. Which of the following would account for the results obtained?

A

Wrong buffer was used; ionic strength higher than required

69
Q

Which of the following applies to reverse-phase liquid chromatography?

A

Polar mobile phase and a nonpolar stationary phase

70
Q

Serum protein electrophoresis (SPE) is normal. CSF electrophoresis shows oligoclonal banding. What clinical significance is there to these findings?

A

This is indicative of multiple sclerosis

71
Q

To be analyzed by gas chromatography, the analyte must be which of the following?

A

Volatile

72
Q

In serum protein electrophoresis (SPE), the buffer used is more acidic than the isoelectric point (pI) of the proteins. How will this affect the charge and migration of the proteins?

A

Proteins will be positively charged and move to the cathode

73
Q

Why does albumin migrate much further than gamma globulin in serum protein electrophoresis (SPE)?

A

Albumin has more negative charges

74
Q

What might be the cause of a narrow band in the β2-γ region?

A

Inadvertent use of plasma for SPE

75
Q

Urine electrophoresis shows large amounts of albumin and increased transferrin. What is the likely cause?

A

Nephrotic syndrome with glomerular proteinuria

76
Q

Using a buffer of 7.4 for serum protein electrophoresis (SPE), where will a protein with an isoelectric point of 6.0 migrate?

A

To anode

77
Q

Which one of the following is most likely to be decreased in an acute inflammatory reaction?

A

Albumin

78
Q

Which of the following is the best way to detect Bence-Jones protein in urine?

A

Immunofixation of urine

79
Q

In which condition would you expect to find high serum total protein but normal albumin?

A

Multiple myeloma

80
Q

Which of the following is true of MALDI-TOF MS analysis?

A

Mass spectrum is unique to bacterial identification,
a proteomic analysis, large ions are slow

81
Q

In mass spectrometry, the degree of bending (deflection) of an ion is inversely proportional to the mass (m) and directly proportional to the charge (z). Which of these ions will bend the most?

A

Ion D with m= 10 and z =+2

82
Q

An automated chemistry instrument establishes the line of best fit for determination of concentration values of unknowns. How is this line of best fit established?

A

By using a linear regression model with calibrator results

83
Q

Which of the following best defines a reference interval (range)?

A

Interval of results expected for a defined healthy population

84
Q

In a normal distribution curve, how many values are included in two standard deviations from the mean?

A

95%

85
Q

In establishing 95% confidence limits for a method in a QC program, how many test results are expected to fall outside the allowable limits?

A

1 in 20

86
Q

What is proportional systematic error dependent on?

A

Analyte concentration

87
Q

For a spectrophotometer to work in the 380-700 nm wavelength range, what is the best light source?

A

Tungsten lamp

88
Q

Which detector is able to measure very low intensities of radiant energy and give a suitable meter response?

A

Photomultiplier cell

89
Q

Which best describes the effect of stray light on the analysis of a sample?

A

%T is falsely increased causing false decrease in absorbance

90
Q

Which of the following applies to photometric measurement of enzyme activity?

A

Enzyme concentration measurement is performed in zero-order kenetics

91
Q

The bandpass of a spectrophotometer is 10 nm. If set at 540 nm, what wavelengths will reach the sample?

A

535-545 nm

92
Q

Which of the following situations will cause an apparent increase in light absorbance?

A

Lipemic Sample

93
Q

How is a double-beam spectrophotometer different from a single-beam spectrophotometer?

A

Double beam permits automatic correction of sample and reference absorbance

94
Q

Which of the following statements regarding light measuring methods is correct?

A

Nephelometers detect light at various angles including 90°

95
Q

Which of the following best describes the principle of fluorometry?

A

Absorption and emission

96
Q

An intoxicated patient arrives to emergency room. They present with vomiting and state they had “one too many” alcoholic beverages. Which of the following is this patient most likely experiencing?

A

Metabolic acidosis & metabolic alkalosis

97
Q

Which of the following situations indicate that an instrument problem is present and requires further investigation?

A

Series of high anion gaps

98
Q

What best describes the pH at which proteins carry a zero electrical charge?

A

Isoelectric point

99
Q

A blood sample collected in a serum tube has been sitting uncapped on the bench for 20 minutes. Which of the following would have occurred?

A

Decreased ionized Ca result

100
Q

An ion specific electrode is used for the measurement of potassium. What is it prepared from?

A

Valinomycin

101
Q

Within what time frame should the blood gas specimens be analyzed?

A

30 minutes

102
Q

What does the pCO2 electrode measure?

A

Change in pH of solution surrounding the electrode

103
Q

Which method properly describes the pO2 measurement?

A

Amperometry

104
Q

Which of the following represent metabolic acidosis?

A

Decrease in HCO3⁻; decreased pH

105
Q

What is the most common cause of erroneous results in blood pH determinations, following several pH sample runs?

A

Protein build up on the electrode

106
Q

Which of the following is an essential component of quality in blood gas analysis?

A

Participating in external proficiency testing

107
Q

For accurate results, what must be done immediately prior to the testing of a blood gas specimen?

A

The sample must be mixed

Clinical Chemistry Practicum (5 decks)

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