Factor V in an Industrial Population

Abstract

Summary. Factor‐V levels have been measured in a random sample of 626 men and 307 women working in a variety of occupations in North West London. The method is an automated one‐stage assay using the same batch of freeze‐dried thromboplastin, all results being expressed in terms of the same freeze‐dried standard plasma; it has been shown that only one dilution of test plasma is necessary. Factor‐V levels are significantly higher when venepuncture is difficult than when it is satisfactory, the mean levels being about 130% and 117% respectively. Factor‐V levels are approximately normally distributed; they are similar in men and women and in blacks and whites, and increase significantly with age at the rate of about 0.6% per annum. Factor‐V levels are not affected by oral contraceptives or the menopause, and there are no differences according to blood group or secretor status.