Application of enzyme immunoassays to coagulation testing.
Enzyme immunoassays are very useful for the detection of low concentrations of coagulation proteins and pathological markers in plasma. Analytes in the ng/mL range are measurable with good reproducibility with intra- and interassay CVs of less than 5% to 10%. "Sandwich" methods have been developed for von Willebrand factor (plasma concentration about 8 micrograms/mL, Factor IX (5 micrograms/mL), protein C (4 micrograms/mL), and Factor X (10 micrograms/mL). However, this technique is only suitable for macromolecules; for low-molecular-mass peptides such as fibrinopeptide A a competitive method is used. Normal concentrations of fibrinopeptide A are below 3 ng/mL, with greater values suggesting in vivo generation of thrombin; thus this test is quite useful in detecting thrombosis. Reagents for both the sandwich and competitive methods are commercially available and cost effective, and have a longer shelf-life than those for radioimmunoassays.
D001667:Binding, Competitive; D001779:Blood Coagulation Factors / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay; D005164:Factor IX / Q000032:analysis; D005170:Factor X / Q000032:analysis; D005344:Fibrinopeptide A / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D007124:Immunoenzyme Techniques; D011486:Protein C; D014841:von Willebrand Factor / Q000032:analysis
D001779:Blood Coagulation Factors; D006023:Glycoproteins; D011486:Protein C; D014841:von Willebrand Factor; D005344:Fibrinopeptide A; D005164:Factor IX; D005170:Factor X