ABSTRACT
The only indicator of vitamin K status with a clearly defined clinical significance is the prothrombin time (PT), and alterations in the PT by changes in dietary intake of vitamin K alone are uncommon to nonexistent. The sensitivity of the immunochemical assays for Proteins Induced by Vitamin K Absence or Antagonists-II is such that very large increases of the nonfunctional form of vitamin K can be observed with no evidence of an alteration in the important physiological function of the prothrombin-driven plasma procoagulant pathway. A clinically significant deficiency of vitamin K is extremely rare and usually results from severe malabsorption syndromes. Diets containing high levels of vitamin A have been reported for some time to adversely influence vitamin K action. The possible relationship between vitamin K status and glucose homeostasis needs additional study before it is accepted and the relationship between the data and the possible role of osteocalcin in the control of energy metabolism also need to be assessed.
