Endocrine Abstracts

Objective: The cardiovascular effects of testosterone treatment are debated. Osteoprotegerin (OPG) is an independent marker of cardiovascular risk. We investigated the effect of testosterone therapy on OPG levels in ageing men with low normal bioavailable testosterone levels.

Design: A randomized, double-blinded, placebo-controlled study of six months testosterone therapy (gel) in 38 men aged 60–78 years with bioavailable testosterone <7.3 nmol/l and waist circumference >94 cm.

Methods: Clinical evaluation, OPG, and C-reactive protein measurements. Bone mineral density (BMD), lean body mass (LBM) and total fat mass were established by dual X-ray absorptiometry and visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were measured by magnetic resonance imaging. Power calculation was based on an increase in LBM during testosterone therapy and responders were defined as testosterone treated patients with increased LBM (ΔLBM positive), n=14. Data were presented as median (interquartile range).

Results: Testosterone therapy decreased total fat mass and SAT, whereas VAT was unchanged (n=38). OPG levels decreased during testosterone therapy (from 2.0 (1.9–2.5) to 1.9 (1.6–2.2) ng/ml, P<0.05 vs placebo), whereas CRP levels were unchanged. In responders for testosterone therapy (n=14), ΔOPG levels were inversely associated with ΔSAT (r=−0.60, P=0.03) and positively associated with ΔVAT (r=0.56, P=0.04). BMD levels were unchanged during testosterone therapy.

Conclusion: OPG levels decreased during testosterone therapy suggesting decreased cardiovascular risk. Decreased OPG levels were associated with changes in regional fat distribution and future studies are needed to further evaluate the association between OPG and regional fat mass distribution.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.