ORLANDO, Fla.—Testosterone supplementation in elderly men with borderline low testosterone levels may not improve erectile dysfunction (ED) compared with placebo, new findings suggest.
“The existing data on this are mixed,” said study investigator Lauren Roth, MD, a second-year fellow in reproductive endocrinology and infertility at the University of Colorado in Denver. “We expected there would be an improvement.”
Dr. Roth reported study findings at the American Society for Reproductive Medicine annual meeting.
She and her colleagues found scores on the Sexual Health Inventory for Men (SHIM) instrument did not improve despite bringing men into the normal androgenic range using transdermal testosterone.
In this study, men aged 60 years or older with borderline low testosterone (T) were treated with low-dose testosterone gel (25 mg/day), conventional-dose testosterone gel (50 mg/day), or placebo gel for one year.
The researchers used two dosing regimens to determine if side effects were dose-dependent. Testosterone levels were measured and SHIM administered at baseline and six and 12 months.
A total of 56 subjects were in the placebo group (P), 56 were in the low-dose T group (T25), and 55 were in the conventional-dose T group (T50). The three groups did not differ significantly in age or in levels of total or free T at baseline. Additionally, all three groups demonstrated mild to moderate ED based on SHIM scores at baseline.
Over the course of the study, total and free T did not change in the placebo group but increased significantly in both treatment groups. However, the investigators observed no change in SHIM scores in any group. “This was surprising,” Dr. Roth told Renal & Urology News. “There have been small studies before that have looked at a similar cohort and [found] an improvement in sexual function, but that included men who were hypogonadal. This was a different group of men who had borderline low testosterone. Men with erectile dysfunction and low testosterone commonly are supplemented with testosterone in an attempt to improve their erectile dysfunction. These data would suggest that it is not beneficial.”
Dr. Roth, who presented the study findings at the meeting, noted that currently there is no defined standard for diagnosing hypogonadism. Most clinicians rely on a laboratory diagnosis (total testosterone below 200 ng/dL) and symptomatic diagnosis or a combination of both.
Studies have shown that there is a normal physiologic decrease in testosterone as a man ages. The Baltimore Longitudinal Study on Aging found that the incidence of low testosterone (below 200 ng/dL) increases significantly after age 60. Researchers have found that low testosterone occurs in 20% of men over age 60, in 30% of men over the age 70, and in 50% of men over the age of 80 (J Clin Endocrinol Metab 2001;86:724-731).
Commenting on the study, Dolores J. Lamb, PhD, President-Elect of ASRM, said these findings may affect clinical practice. “Studies in animal models show that the neural control of sexual motivation and functioning is complex with ‘cross-talk’ of many signaling pathways that ultimately influence sexual behavior,” said Dr. Lamb, Professor, Department of Urology, Baylor College of Medicine in Houston. “This study indicates that perhaps testosterone supplementation is needed for some men, some of the time. Nevertheless, studies like these should make men cautious about the use of androgens to counter the effects of aging on sexual function.”