Unit 1 - Intro to BioChem Flashcards by Melanie Laird

Biochemistry Definition

Analysis of the chemical composition of human specimen

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Pre-Analytical Phase

Specimen Collection
Specimen Handling
Specimen Processing

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Analytical Phase

Calibration
Control
Critical Action Value
Reference Intervals
Delta Check

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Post Analytical Phase

Reporting
Critical Action Value
Clinical Decision Limit

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When would centrifugation take place?

Pre-Analytical Phase

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When would temperature control storing take place?

Pre-Analytical Phase

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What should have traceability?

Calibrator/Standard

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What material has a known value?

Calibrator
Control

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Unknowns are compared to what?

The calibrator/Calibration curve

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Unknowns are NOT compared to what?

The control

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What is meant to evaluate the instrumentation’s performance?

Control

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How are control values determined?

Comparing them to calibrator

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Control won’t detect problems in…

Individual specimens

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Controls should have what?

Commutability

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What is commutability?

The ability to compare controls and human specimen even if their makeup is different

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In a Gaussian Distribution, There is no guarantee that a sick person will fall….

outside of the reference range

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What is evaluated during both analytical and postanalytical phases?

Critical Action Value

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What are clinical decision limits?

Dictates when treatment is necessary

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When is read back required?

Critical Action Value

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Which is more urgent? clinical decision limit or critical action value

Critical action value

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Venous Blood

Lower Oxygen
Higher CO2
Lower glucose

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How can venous blood be analyzed?

Whole Blood
Plasma
Serum

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How can arterial blood be analyzed?

Whole Blood

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Arterial blood

Higher O2
Lower CO2
Higher glucose

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Why is glucose higher in arterial blood

Its being transported to the tissues

Capillary/Skin Puncture

Mixture of arterial blood and venous blood

What is the downside of capillary blood?

Contamination

How can capillary blood be analyzed?

Whole Blood Plasma Serum

Midstream catches are useful when?

Detects UTI or bacterial infection

Untimed/Random Urine Specimen

Clean, fasting, early morning Midstream

Timed Urine Specimen

Avoids dilution Over a period of time

Preservatives in urine specimen

For 24hr timed specimen Reduces bacterial growth Prevents decomposition Can interfere with testing

Fecal specimen

No preservatives Refrigerate for long collection periods

When is CSF analyzed

Immediately

What is the first CSF tube for?

Chemistry since it has most contamination

What is the second CSF tube for?

Microbiology since contaminating organisms should've been flushed out

Why is the third CSF tube for?

Microscopy/Cytology (cell counts) Since most sterile

What is the process of removing fluid from synovial joints called?

Arthrocentesis

What is the process of removing amniotic fluid called?

Amniocentesis

What is paracentesis?

Sterile procedure for enclosed body sites

What are uncontrollable factors that affect specimen composition?

Biological Environmental Underlying health conditions

Fasting definition

No food or liquid other than water 8-12 hr

Post-prandial definition

After a meal/ingestion of standard nutrient 2hr for glucose

IV drawing options

1st: Other arm 2nd: Below IV 3rd: Turn IV off 2min, draw above

What happens to blood volume after going from lying down to standing up?

Blood volume reduced by 9% for 30 minutes

Patient identification protocols

Check armbands when present Photo ID Speak FN, LN, DOB Verify with caregiver/family if nonverbal

What must be done before leaving the patient after a specimen collection?

Confirm armband and specimen Ask patient to verify label

When should plasma/serum be separated?

Less than 2 hours

What can premature separation do?

Lead to continued clotting of serum after separation

What does evaporation of serum/plasma do to analyze concentration?

False increase

What happens to volatile analyses in an improperly sealed/capped tube?

False decrease as it escapes

Room Temp for storage

25ºC

Refrigerator Temp for Storage

2-8ºC

Freezer temp for storage

-10º to -20ºC

Hemolysis absorbance peak

415 nm

Icterus Absorbance Peak

~454 nm

Lipemia absorbance peak

~700 nm

3 strategies to handle HIL flags

Report results Cancel Test Dilute specimen

Two Types of IN VIVO hemolysis

Extravascular Intravascular

Extravascular hemolysis

RBC defects causing lysis Infections in RBC (malaria) Autoimmune hemolytic anemia Excess spleen activity

Intravascular hemolysis

Microangiopathy Transfusion reaction Infections like malaria and sepsis Hemolytic disease

In vitro hemolysis

Blood draw Frozen specimen Shaking Delay

When does the Analytical Phase begin?

When specimen retrieved from storage and verify acceptability

Quality Control

Error detected

Quality Assurance

Error prevented

Error Cannot:

Invalidate medical usefulness of result or Cause lab to fail proficiency testing

What is random error

Method imprecision Cannot escape it ±4SD

What is systematic error formula

observed value minus accepted value (x - u)

What is total error

Systematic error plus random error

Value alone is not enough. What other information must accompany it?

Reference interval Type or condition of specimen

What are controls compared to?

Calibrators

What is systematic error?

The measured value either consistently above or below the actual value

Is systematic error ever okay?

Yes as long as it doesn't invalidate medical usefulness

What are the two components of systematic error?

Constant error Proportional error

What does method insensitivity do to the value of an analyte?

False depression

What does oversensitivity do to the value of an analyte?

False elevation

What does diabetes do to glucose levels?

Increases them since insulin isn't working

What does kidney disease do to waste levels?

False increase

What does collection above an IV site do to analyte levels?

Hemodilution

Can a critical action value be sent by paper?

No, requires read back and verbal communication

What is required to accurately aspirate specimen?

Dead volume

What are the problems with capillary punctures?

Hemolysis Contamination Difficult blood flow

Can small children and neonates have blood drawn using evacuated tubes?

Not really, the vacuum can collapse veins

How should you collect urine from a small child or neonate?

Adhesive bag

What is not recommended for capturing urine in small children and neonates?

Cotton balls, especially for microscopic because of the fibers

Beers law calculation

(Unk Abs * Std Conc) / (Std Abs)