Description and evaluation of a new chromogenic substrate assay kit for the determination of prekallikrein in human plasma.

Because of an increasing interest in the determination of prekallikrein a kit was made for the determination of this plasma proenzyme. The kit consists of 1) a prekallikrein activator of the cephalin-ellagic acid type containing Factor XII and HMW-kininogen to ensure a total activation of the prekallikrein even in pathological plasmas, 2) a buffer which is optimal for both activation and substrate hydrolysis and 3) the chromogenic substrate S-2302. A control plasma is also included. This kit was evaluated by thirteen research groups as well as by ourselves. Both normal and patient plasmas were analyzed. Good correlations were obtained for prekallikrein levels in plasma samples between the kit method and two other methods (immunochemical and functional). As well as in deficiency states the prekallikrein level was low in pancreatitis (n = 20), cancer (n = 16), early pregnancy with gestosis (n = 15), cirrhosis (n = 9) and cases with thromboembolic disorders (n = 5). The prekallikrein level was high in late pregnancy (n = 4).