The synthesis and catabolism of both prothrombin and PIVKA-II were studied in patients
with stable stage of various thromboembolic disorders. Laboratory examinations revealed
that their hemostatic and fibrinolytic activities were within normal range. Thirty
mg of warfarin was administered orally to patients, which was followed by daily U
to 8 mg of warfarin to maintain one stage prothrombin time in therapeutic range. Fifty
mg of vitamin K was administered intravenously to these anticoagulated patients. PIVKA-II
was determined as prothrombin related antigen in the BaSO^ adsorbed plasma by the
method of Ganrot using anti-human prothrombin antibody.
After the administration of 30 mg of warfarin, prothrombin clotting activity(FII:C)
decreased exponentialy with the half life(T 1/2) of 74 hrs on an average. Rapid increase
of PIVKA-II was observed in the early phase of warfarin administration, though in
the later phase an increasing tendency slowed down. The changes of PIVKA-II in the
early phase could be analyzed easier by following up the changes in the value of (100
- PIVKA-II activity)%. As the progress of time after the administration of warfarin,
their values decreased exponentialy with the T 1/2 of 64 hrs on an average. After
the administration of vitamin K, FII:C increased rapidly in the initial phase, then
slowly returned to normal level. Similarly to the case of PIVKA-II after the administration
of warfarin , values of (100 - FII:C activity)% decreased exponentialy with the T
1/2 of 45 hrs on an average. PIVKA-II decreased rapidly after the administration of
vitamin K, describing exponential curve with the T 1/2 of 40 hrs on an average.
From the results described above, it is suggested that the catabolism of PIVKA-II
is much more faster than that of FII:C.
