understanding lab tests Flashcards
decision limit of troponin
detectable troponin concentrations above the 99th percentile represent myocyte damage
–this is not standardized, so consult reference interval
Reference Interval
interval of values that encompass 95% of normal population
5% of “normal individuals” will be outside of this interval
reference interval for non-diabetics
4.3-6.1%
target of therapy for DM
7%
critical test
any test that always require rapid communication to the ordering provider whether results are normal or not
critical results
any lab finding (STAT or routine) that requires a rapid communication of results
pre-analytical
phys deciding to test, order entry, patient preparation, specimen collection, processing and transport
analytical
receiving specimen, analysis, and result verification
post analytical
physician acknoledging result, interpretation, and implementation of treatment course (if necessary)
most variation (error) occurs
pre-analytic stage
preanalytic variation
- order entry errors
- patient prep- fasting, exercise/posture, timing of collection
- specimen collection- similar names, needle size, tube slection, urine preservatives
- processing, storage, transport
post analytic variation
- transcription errors
- calculation errors
- errors in result interpretation
spectral interference
hemolysis
icterus (jaundice)
lipemia (blood in emulsified fat)
==change in absorbance at specific wavelength for measurement; related to analyte concentration
hook effect
false negative due to very high concentrations of a particular analyte
–excess antigen, so host antibodies bindall antigen and your antigen cant bind anything
Heterophile Antibody/HAMA
person’s antibody ecognizes antibodies used in the assay (may be anti Fc or anti Fab antibodies)
–can result in false positives or false negatives
