Citrated Plasma (light blue top)
Additional Sample Requirements
Protein C activity is measured by chromogenic method. Patients should be off warfarin for at least 2 weeks before drawing a sample. The assay kit manufacturer has demonstrated the assay to be unaffected by therapeutic levels of unfractionated heparin, low molecular weight heparin, dabigatran and rivaroxaban, but aprotinin may cause falsely reduced protein C activity results. Pathologic samples that have undergone contact activation may result in falsely elevated protein C activity. Age-dependent reference intervals are used.
Additional Sample Information