Age- and sex-related differences of plasma activated factor VII levels in children.

Although the majority of factor VII (FVII) circulates in the zymogen form, low levels of activated factor VII (FVIIa) exist in plasma and play an important role in the initiation of tissue factor-induced coagulation. It has been reported that the concentrations of hemostatic components in children and adults are different. Here, we investigated the age- and sex-related differences of FVIIa and FVII antigen (FVIIag) levels in children at age of 10 (n = 123; males: n = 62; females: n = 61), and 13 (n = 105; males: n = 47: females: n = 58), and compared these levels with those of young adults (mean +/- SD of age: 29.6+/-6.0 years). In males, there was not a significant difference between the FVIIIa levels of 10-year-old children and 13-year-old children, but the FVIIa levels in adult controls were significantly higher than those in children. In females, the FVIIa levels in 13-year-old children were significantly higher than that in 10-year-old children, but there was not a significant difference between 13-year-old children and adults. Thus, our study showed that plasma FVIIa levels were lower in children than in adults, and the increase of FVIIa level was earlier in females than in males.