Biochemical vitamin K deficiency in early infancy: diagnostic limitation of conventional coagulation tests.

Thrombotest, factor II and factor X determinations were performed in two groups of children, one receiving a low vitamin K diet (breast-feeding) and one receiving a high vitamin K regimen (formula-feeding). No infant received vitamin K at birth. Thrombotest values were found to be lower at day 30, 60 and 90 after birth, and factor II levels unexpectedly higher at day 30 and 60 in breast-feeding group compared to the formula-feeding group. No difference in factor X levels could be detected. Compared to the direct measurement of PIVKA II by a highly sensitive immunological method, these coagulation tests are inadequate to detect biochemical vitamin K deficiency.