This study was designed to determine if testosterone could improve older men's ability to get around, given that the hormone has already been shown to boost muscle strength.
Just over 200 men aged 65 or older with low testosterone levels and mobility problems were randomly assigned to receive testosterone gel or a placebo daily for six months.
Many of the participants started out in poor health, with higher blood pressure, cholesterol and obesity levels, and higher rates of diabetes and heart disease.
The trial was discontinued at the end of 2009 when researchers found that 23 men in the testosterone group had had cardiovascular problems including heart attacks and hypertension, compared with only five in the placebo arm. Participants taking testosterone also had more respiratory and skin-related side effects.
The men in the testosterone arm of the study did see gains in muscle strength and their ability to climb stairs, said Bhasin, who is chief of the division of endocrinology, diabetes and nutrition at Boston University School of Medicine.
But, he added, "these potentially beneficial effects on muscle strength were mitigated by the serious cardiovascular adverse events in men assigned to testosterone arm of the study."
Six other NIA-funded trials on testosterone are continuing, Hadley said.
There's more on low testosterone at the U.S National Library of Medicine.
SOURCES: Shalender Bhasin, M.D., chief, section of endocrinology diabetes and nutrition, Boston University School of Medicine; Evan Hadley, M.D., director, division
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