(HealthDay News) – Testosterone testing and supplementation have increased substantially over the last decade, with many men in the United States initiating treatment even though they have normal levels, according to a study published online Jan. 1 in the Journal of Clinical Endocrinology & Metabolism.

J. Bradley Layton, PhD, from the University of North Carolina at Chapel Hill, and colleagues analyzed 2000–2011 data from 410,019 U.S. men and 6,858 U.K. men who began taking testosterone, and from 1,114,329 U.S. men and 66,140 U.K. men who had their testosterone levels measured.

The researchers found that testosterone initiation almost quadrupled among U.S. men (from 20.2 to 75.7 per 10,000 person-years), while increasing by only a third among U.K. men (from 3.4 to 4.5 per 10,000 person-years). Many had not had a recent testosterone test prior to initiation. Testing increased in both the United States and the United Kingdom, but testing identified more men with low testosterone in the United Kingdom, while more men with normal levels were tested in the United States. Men in the United States also tended to initiate testosterone at normal levels. In both the United States and the United Kingdom, gels have become the most common initial treatment.

“Testosterone testing and use has increased over the past decade, particularly in the United States, with dramatic shifts from injections to gels,” Layton and colleagues conclude. “Substantial use is seen in men without recent testing and in U.S. men with normal levels.”

Several authors disclosed financial ties to the pharmaceutical industry.

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