title: Variability in total testosterone levels in ageing men with symptoms of androgen deficiency.
abstract: The aim of this study was to determine the variability in total testosterone (TT) levels in healthy, non-obese ageing men with symptoms of androgen deficiency. Men aged ≥55 years were recruited from the community. Morning TT levels were measured on four occasions in a 12-month period. In all, 96 men aged 62.7 ± 6.8 years were studied. Geometric mean values (95% confidence interval) of TT levels for the cohort at each time point were 14.5 (13.4-15.7), 14.6 (13.5-15.8), 15.5 (14.4-16.8) and 15.0 (13.9-16.2) nmol/L. The maximum intra-individual difference in TT between the four samples was 4.1 nmol/L (interquartile range: 2.9-6.4). Using the average of two baseline TT values reduces the maximum difference to 2.3 nmol/L (1.0-3.8). Only 1 of 25 men with a documented TT <10 nmol/L at baseline had TT levels <10 nmol/L at all subsequent time points. A single TT level is a reliable predictor of repeat measures taken within a 12-month period for a cohort of healthy ageing men with symptoms of androgen deficiency. However, given that the diagnostic criteria for androgen deficiency are, in part, predicated upon serum TT, there is sufficient intra-subject variability to warrant repeat sampling to confirm an initial low TT level. Using an average of two baseline TT values reduces this variability.
authors.affiliation: Prince Henry's Institute, Clayton, Victoria, Australia.
authors.forename: C A
authors.initials: CA
authors.lastname: Allan
authors.forename: B J G
authors.initials: BJ
authors.lastname: Strauss
authors.forename: E A
authors.initials: EA
authors.lastname: Forbes
authors.forename: E
authors.initials: E
authors.lastname: Paul
authors.forename: R I
authors.initials: RI
authors.lastname: McLachlan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood; D000728:Androgens / Q000172:deficiency*; D015331:Cohort Studies; D006801:Humans; D007006:Hypogonadism; D008297:Male; D008875:Middle Aged; D013739:Testosterone / Q000097:blood* / Q000172:deficiency*
chemical_list: D000728:Androgens; D013739:Testosterone