A plasma protein C activity assay suitable for a clinical laboratory. Its use to measure activity in hereditary and acquired deficiency states

S. I. Rapaport, A. Zivelin, K. Donnelly

Research output: Contribution to journalArticlepeer-review

Abstract

The authors describe the technic and standardization of an assay to measure plasma protein C activity feasible for clinical laboratory use. It is modified from an assay of Francis and Patch (Thromb REs 1983; 32: 605-613) to enhance protein C recovery in the barium citrate eluate, to eliminate the steps of addition and neutralization of heparin, and to use only commercially available reagents. The normal range for plasma protein C in the assay is 72-130% (±2 SD) (0.7-1.30). Hepatocellular disease lengthening the prothrombin time by 3-4 seconds was associated with plasma protein C activity of 25% (0.25) to 35% (0.35). Although the assay is thought to accurately measure protein C activity in patients taking warfarin, one cannot evaluate such patients for hereditary functional protein C deficiency because treatment with warfarin will itself reduce the ratio of protein C activity to antigen. The assay can be used in a patient receiving heparin if the heparin is removed as described.

Original languageEnglish
Pages (from-to)491-497
Number of pages7
JournalAmerican Journal of Clinical Pathology
Volume87
Issue number4
DOIs
StatePublished - 1987
Externally publishedYes

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