Factor V (proaccelerin) concentration in 1016 blood donors. The effects of age, sex, and ABO blood groups.

Factor V (proaccelerin) concentration was measured in the plasma of 1016 regular and controlled blood donors. Age had a highly significant effect on factor V concentration. The median rose from 99 per cent at the age of 20 to 123 at the age of 60 years. Minor effects of sex and ABO blood groups were suggested. Interactions between these factors were found negligible. Accuracy and precision of the assay method and the use of percentiles in the laboratory reports are discussed. The results may support the hypothesis of relation between high concentration of coagulation factor V and predisposition to thrombosis.