title: Influence of demographic factors on antithrombin III activity in a healthy population.
abstract: Antithrombin III (AT III) activity has been measured in 9669 healthy blood donors (5525 male and 4144 female). The distribution of AT III is approximately 'normal' with mean 105.6 IU/dl and standard deviation 11.2; however, definite age and sex related variations are evident. Pre-menopausal females have lower mean AT III compared to their male contemporaries who have remarkably stable mean AT III until 45 years, after which there is a gradual decline. In contrast, post-menopausal females have higher mean AT III than both males of the same age and younger pre-menopausal females. Concurrent hormone replacement therapy inhibits this rise. The use of hormonal preparations is associated with a 4 IU/dl reduction of mean AT III in younger females but not in those over 30 years. Smoking may result in a mild increase in AT III of doubtful clinical significance. On-going genetic and family studies are expected to predict a prevalence rate of congenital AT III deficiency in excess of the previously reported figure of 0.02%. The authors consider these observed variations as minor and recommend the use of a single reference range for AT III activity, but that particular care be taken when interpreting results in pill-taking females and the elderly.
authors.affiliation: Department of Haematology, Royal Infirmary, Glasgow, Scotland.
authors.forename: R C
authors.initials: RC
authors.lastname: Tait
authors.forename: I D
authors.initials: ID
authors.lastname: Walker
authors.forename: S I
authors.initials: SI
authors.lastname: Islam
authors.forename: F
authors.initials: F
authors.lastname: McCall
authors.forename: J A
authors.initials: JA
authors.lastname: Conkie
authors.forename: R
authors.initials: R
authors.lastname: Mitchell
authors.forename: J F
authors.initials: JF
authors.lastname: Davidson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood; D000990:Antithrombin III / Q000187:drug effects / Q000378:metabolism*; D003276:Contraceptives, Oral / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D008593:Menopause / Q000097:blood; D008875:Middle Aged; D012016:Reference Values; D012737:Sex Factors; D012907:Smoking / Q000097:blood
chemical_list: D003276:Contraceptives, Oral; D000990:Antithrombin III