(28) Another such protein is des-carboxy-prothrombin (PIVKA-II), the undercarboxylated forms of prothrombin, a vitamin K-dependent clotting factor
synthesized in the liver.
One reason is that, unlike osteocalcin in bone, in the average healthy population clotting factors in the liver are fully carboxylated: "The vitamin K-dependent clotting factors
are all produced in the liver and, in contrast to osteocalcin, they are all fully carboxylated in the healthy population."
A study using vitamin K1 (150 [micro]gm phytomenadione) daily in patients with unstable anticoagulation control showed that increasing and stabilizing the body's stores of the vitamin allowed for better control of anticoagulation by maintaining steady activation of vitamin K-dependent clotting factors
The differential diagnosis includes dysfibrinogenemia, prothrombin deficiency, factor V deficiency, combined deficiency of factors V and VIII (F5F8D), factor X deficiency, and hereditary combined deficiency of the vitamin K-dependent clotting factors
. All of these conditions feature prolongation of both the PT and the aPTT (1).
(2) Superwarfarin exposure must be included in the differential diagnosis when a patient presents with deficiency of vitamin K-dependent clotting factors
and has a limited response to vitamin K supplementation.
These are more sensitive to a reduction in vitamin K-dependent clotting factors
than are the rabbit brain thromboplastins commonly used on this continent.