title: Does early morning versus late morning draw time influence apparent testosterone concentration in men aged > or =45 years? Data from the Hypogonadism In Males study.
abstract: The Hypogonadism In Males study estimated the prevalence of hypogonadism in men aged > or =45 years. A sub-analysis of patients not receiving testosterone (T) therapy was conducted. Blood draw times were 0800-1000 and 1000-1200 hours. Total T (TT) was not influenced by draw time for any age group; however, significantly greater free T (FT) and bioavailable T (BAT) values were observed in the overall population for earlier draw times. Sex hormone-binding globulin (SHBG) values were significantly lower in men aged 45-64 years at the earlier draw time. In men aged > or =75 years, no significant differences in TT, FT, BAT or SHBG were observed on the basis of draw time. Early morning draw time may not be critical for capturing TT concentrations in men > or =45 years; however, when measuring FT or BAT, an early morning draw time may be preferable for men aged <75 years.
authors.affiliation: Department of Endocrinology, Center for Sexual Function, Lahey Clinic, One Essex Center Drive, Peabody, MA 01960, USA. Andre.T.Guay@lahey.org
authors.forename: A
authors.initials: A
authors.lastname: Guay
authors.forename: M G
authors.initials: MG
authors.lastname: Miller
authors.forename: C L
authors.initials: CL
authors.lastname: McWhirter
mesh_terms: D002940:Circadian Rhythm; D003430:Cross-Sectional Studies; D006801:Humans; D007006:Hypogonadism / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012738:Sex Hormone-Binding Globulin / Q000032:analysis*; D013739:Testosterone / Q000097:blood*
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone