Abstract
When vitamin K deficiency occurs, precursor forms of vitamin K dependent coagulation factors which are termed protein induced by vitamin K absence (PIVKAs) appears in the circulating blood.
Crossed immunoelectrophoresis has usually been employed to demonstrate the presence of PIVKAs, but the procedure is time consuming for clinical use.
In the present test method developed by the authors, the abnormal form of prothrombin (PIVKA-II) in the plasma can readily be determined within a period of 30min. This test method is a simple and rapid assay for the detection PIVKA-II.
The principle of this assay is based on the agglutination of antihuman prothrombin rabbit IgG coated latex (AP-Latex) with absorbed plasma which is treated with barium carbonate.
After mixing with 25μl of the plasma and 200μl of the 0.2% bovine albumin saline, in which 100mg/ml of bairum carbonate was suspended, incubation at 37°C or room temperature for 10min was carried out with shaking every 2min. After the incubation, 275μl of the bovine albumin saline solution was added and the mixture was centrifuged at 3000rpm for 5min. Then 100μl of the supernatant placed on a glass slide (2×3cm), one drop of Ap-Latex was added. After the mixture was shaked for 2min, the latex agglutination was checked in daylight against a flat dark background.
The level of PIVKA-II was expressed by the maximum dilution level being agglutinated in the specimen.
This assay is expected to be useful as a screening test to differentiate whether or not vitamin K deficiency is present in various clinical cases.
