Some potential adverse metabolic effects — and no functional or cognitive benefits — were reported.
The progressive decline in testosterone levels as men age has led to suggestions that physical, functional, or cognitive benefits could accrue from testosterone supplementation later in life. In a double-blind Dutch study, 237 healthy men (mean age, 67) with low-normal circulating testosterone levels (mean baseline total testosterone level, 308 ng/dL) were randomly assigned to oral testosterone undecenoate (80 mg twice daily) or placebo for 6 months. More than 90% of participants used at least 80% of their assigned medication.
At 6 months, total, free, and bioavailable testosterone levels were actually slightly lower with the active preparation than with placebo; the investigators attribute this finding to measuring fasting (and not post-dose) levels. No between-group differences were reported in a structured health assessment or in tests of isometric grip or leg extension strength, functional mobility or strength, cognitive function, bone-mineral density, or body-mass index. Although fasting glucose and insulin sensitivity improved slightly in the treatment group compared with the placebo group, a nearly significant increase in the proportion of men who met criteria for metabolic syndrome (48% vs. 36%) also occurred in the treatment group, mostly attributable to a decrease in HDL cholesterol levels (mean decrease, 3.87 mg/dL). No significant differences were reported in overall quality of life, nor in any safety parameters (e.g., prostate-specific antigen levels, liver function tests).
Comment: In this study, follow-up was short, and the researchers failed to document increased testosterone levels in recipients of testosterone supplements. In any case, these results do not generate enthusiasm for routine testosterone supplementation in men with low-normal testosterone levels. The possibility of higher risk for developing the metabolic syndrome is worrisome.
— Thomas L. Schwenk, MD
Published in Journal Watch General Medicine January 10, 2008
Emmelot-Vonk MH et al. Effect of testosterone supplementation on functional mobility, cognition, and other parameters in older men: A randomized controlled trial. JAMA 2008 Jan 2; 299:39.