A simple assay method for factor X (Stuart-Prower factor).

ConclusionA new assay method for factor × is described. Human plasma is treated with bentonite resulting in a substrate rich in prothrombin but deficient in factors VII and X. Factor V and fibrinogen are also depleted but these factors are replaced by addition of Al(OH)3-treated plasma. Russell viper venom is used to compensate for the factor VII deficiency. The method is a simple and reproducible one. The results obtained compare well with the original method using plasma from a patient with a congenital deficiency of factor X.