Unit 1 - Intro to BioChem Flashcards
Biochemistry Definition
Analysis of the chemical composition of human specimen
Pre-Analytical Phase
Specimen Collection
Specimen Handling
Specimen Processing
Analytical Phase
Calibration
Control
Critical Action Value
Reference Intervals
Delta Check
Post Analytical Phase
Reporting
Critical Action Value
Clinical Decision Limit
When would centrifugation take place?
Pre-Analytical Phase
When would temperature control storing take place?
Pre-Analytical Phase
What should have traceability?
Calibrator/Standard
What material has a known value?
Calibrator
Control
Unknowns are compared to what?
The calibrator/Calibration curve
Unknowns are NOT compared to what?
The control
What is meant to evaluate the instrumentation’s performance?
Control
How are control values determined?
Comparing them to calibrator
Control won’t detect problems in…
Individual specimens
Controls should have what?
Commutability
What is commutability?
The ability to compare controls and human specimen even if their makeup is different
In a Gaussian Distribution, There is no guarantee that a sick person will fall….
outside of the reference range
What is evaluated during both analytical and postanalytical phases?
Critical Action Value
What are clinical decision limits?
Dictates when treatment is necessary
When is read back required?
Critical Action Value
Which is more urgent? clinical decision limit or critical action value
Critical action value
Venous Blood
Lower Oxygen
Higher CO2
Lower glucose
How can venous blood be analyzed?
Whole Blood
Plasma
Serum
How can arterial blood be analyzed?
Whole Blood
Arterial blood
Higher O2
Lower CO2
Higher glucose
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)
