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Testosterone Study Highlights Role of Estrogen in Male Hypogonadism

By Kelly Young

Androgen deficiency reduces muscle mass and strength in men; estrogen deficiency is associated with increase in fat mass; and deficiencies in both impair sexual function, according to an industry-supported study in the New England Journal of Medicine.

Some 200 healthy men aged 20 to 50 years first received goserelin acetate for suppression of estradiol and testosterone. They were then randomized to various doses (0-10 g) of daily 1% testosterone gel for 16 weeks. Another cohort of 200 men were similarly treated and also given anastrozole daily to inhibit the aromatization of testosterone to estrogen, leading to an estrogen-deficient state.

In the first cohort, patients who received low doses of testosterone saw increases in body fat percentages and reductions in lean mass. In the second cohort, the percentage of body fat increased in all groups as aromatization was blocked. In both cohorts, sexual desire declined and erectile dysfunction worsened with lower doses of testosterone.

The authors conclude: "Our finding ... indicates that estrogen deficiency is largely responsible for some of the key consequences of male hypogonadism and suggests that measuring estradiol might be helpful in assessing the risk of sexual dysfunction, bone loss, or fat accumulation in men with hypogonadism."