Dose-response effects of sex hormone concentrations on body composition and adipokines in medically castrated healthy men administered graded doses of testosterone gel

Abstract

Objective

Serum sex steroid concentrations may alter body composition and glucose homeostasis in men in a dose-response manner. We evaluated these endpoints in healthy men rendered medically castrate through use of a gonadotropin-releasing hormone antagonist (acyline) with incremental doses of exogenous testosterone (T) gel.

Design

Subjects (n=6-9 per group) were randomly assigned to injections of acyline every 2 weeks plus transdermal T gel (1.25 g, 2.5 g, 5.0 g, 10 g or 15 g) daily or double placebo (injections and gel) for 12 weeks.

Patients

Healthy men, ages 25-55 years, with normal serum total T concentrations.

Measurements

Serum T, dihydrotestosterone (DHT) and estradiol (E2) were measured at baseline and every 2 weeks. Body composition was analyzed by dual-energy x-ray absorptiometry at baseline and week 12. Fasting serum adiponectin, leptin, glucose and insulin concentrations were measured at baseline and week 10.

Results

Forty-eight men completed the study. A significant treatment effect was observed for change in lean mass (ANOVA p=0.01) but not fat mass (p=0.14). Lean mass increased in the 15g T group relative to all lower dose groups, except the 10g T group. When all subjects were analyzed together, changes in lean mass correlated directly and changes in fat mass correlated inversely with serum T, E2 and DHT. No changes were noted in serum glucose, insulin, or adipokine levels.

Conclusions

In healthy men higher serum concentrations of T, DHT and E2 were associated with greater increases in lean mass and decreases in fat mass but not with changes in serum glucose, insulin, or adipokines

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