Representativeness of a single point plasma testosterone level for the long term hormonal milieu in men

Abstract

To test the reliability of a single plasma testosterone (T) or dihydrotestosterone (DHT) level, respectively, as a parameter of the long term hormonal milieu, plasma T and DHT levels were measured eight times, over a period of 50 weeks, in 169 middle-aged and elderly men with symptomatic benign prostatic hyperplasia, who were otherwise healthy. The results show an excellent correlation (r = 0.849) between plasma androgen levels at first sampling and the mean of the 7 samples taken subsequently over 1 yr. Of the 22 subjects with plasma testosterone levels below the lower limit of normal (10 nmol/L) at first sampling, none had an annual plasma T value greater than 13.5 nmol/L, i.e. the annual mean was also below the normal limit or in the low normal range, whereas of the 18 subjects with a T level at first sampling above 25 nmol/L (+/- 90th percentile), none had a mean plasma T level below 19.0 nmol/L (70th percentile). Similar results were obtained for DHT. When plasma testosterone levels at first sampling were subdivided into groups, with a concentration interval of 5 nmol/L from 5 to more than 25 nmol/L, multifactor analysis of variance showed no significant difference between the values within the same group at each sampling, whereas at each sampling the groups remained highly significantly (P less than 0.001) different from each other. The same applies to DHT levels when subdivided into groups with a concentration interval of 0.5 nmol/L. It is concluded that in healthy middle-aged and elderly men, single point plasma androgen measurements reflect fairly reliably the annual mean androgen level.

The decline of serum testosterone levels in community-dwelling men over 70 years of age: descriptive data and predictors of longitudinal changes

“…Nevertheless, it has been shown previously that single timepoint estimates are a valid approach for population studies (39). Further, bioelectrical impedance analysis has been shown to have a suboptimal accuracy and is limited by various factors for assessing body composition, which could possibly mask associations of baseline body composition with subsequent changes in testosterone levels.…”

The effects of diet on circulating sex hormone levels in men

“…Due to the known circadian variation of adrenal and gonadal steroid concentrations within individuals (Goldman et al 1985;Cooke et al 1993), the majority of studies have ensured that all blood samples were taken at the same time of day. A single measurement of circulating serum testosterone and DHT concentrations has been shown to re¯ect mean annual androgen concentrations in middle-aged men reliably, with a Pearson's correlation coef®cient of 0Á85 between the ®rst sample and the mean of seven subsequent samples taken over a 1-year period (Vermeulen & Verdonck, 1992). The within-subject variation of testosterone and SHBG measurements taken from men over a 12-month period have been reported to be substantially less than the between-subject variability (Valero-Politi & Fuentes-Arderiu, 1993).…”

The Role of Alcohol and Steroid Hormones in Human Aggression

“…In addition, there is a seasonal variation with peak concentrations between May and July (Zitzmann and Nieschlag, 2001), which could have also affected the outcome. The day-to-day reliability of testosterone is high varying from 0.64 (Dabbs, 1990) to 0.85 (Vermeulen and Verdonck, 1992). Among middle-aged men, the reliability is higher because of decreased diurnal and seasonal variability (e.g.…”