Clinical Tests for Metabolites and Biomarkers Flashcards
what is a biomarker?
a protein or small molecule for which changes correlate with disease states
what is a standard curve?
a curve defined using reference samples with known conentrations; can be used to interpolate patient values
out of range when above or below the standard curve
what are two types of detection tests?
enzymatic assay and ELISA
how do enzymatic assays work?
use synthetic metabolites to detect patient enzymes
OR
use synthesized enzymes to detect patient metabolites
what is kcat?
rate constant of second step
how does a change in enzyme concentration affect vmax?
more enzymes = higher vmax
how does an ELISA work?
use synthesized antibody to detect patient antigen: metabolite or biomarker
OR
use synthesized antigen to detect patient antibody: pathogen exposure or auto-antibody
what are advantages to using an ELISA?
antibody-antigen interaction has high affinity, is not easily disrupted, has good specificity
each antibody has 2 identical binding sites for antigen
what are sources of a false positive ELISA?
cross reactivity
what are sources of a false negative ELISA?
antigen level below detection limit
OR
body hasn’t made an antibody yet (2 weeks)
what biomarker is the gold standard for AMI detection?
troponin I
what time frame is best for troponin detection?
begins to appear after 4 hours post MI , peaks at 24 hours
