Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2009) 20 P444

ECE2009 Poster Presentations Obesity and Metabolism (70 abstracts)

Letrozole normalizes serum testosterone and reduces body weight in morbidly obese men with obesity-related hypogonadotropic hypogonadism

Sandra Loves , Jos de Jong , Adriaan van Sorge , Darryl Telting & Hans de Boer


Rijnstate Hospital, Arnhem, the Netherlands.


Introduction: Hypogonadotropic hypogonadism is frequently observed in morbidly obese men, due to aromatase-dependent conversion of androgens to estrogens in adipocytes. The clinical impact of this sex hormone imbalance is not known.

Aim: To evaluate the clinical effects of aromatase inhibition in obesity-related hypogonadotropic hypogonadism.

Methods: Double-blind, placebo-controlled trial for 6 months in severely obese men (BMI > 35 kg/m2) with obesity-related hypogonadism (serum total testosterone < 10 nmol/l). Predefined drug regimen: Starting dose 1 tablet/week, subsequent dose escalation up to a maximum of 7 tablets/week or until a serum total testosterone of 20 nmol/l.

Results: So far, 16 patients have completed the study, 8 on letrozole (mean dose: 2 tablets/week) and eight receiving placebo (mean dose: 7 tablets/week). Both groups were well matched for all study parameters. Age (mean±S.E.M.) 40.6±1.6 years, BMI 43.5±1.3 kg/m2, serum LH 3.6±0.4 U/l, total testosterone 7.2±0.4 nmol/l, free testosterone 214.5±14 pmol/l, total estradiol 127.5±11.7 pmol/l. Six months of Letrozole treatment decreased serum estradiol by 53.3±20.5 pmol/l (P<0.05) and increased serum LH by 6.4±1.6 U/l (P<0.005). Total testosterone rose by 12.8±1.2 nmol/l (P<0.0001), and free testosterone by 412±52 pmol/l (P<0.0001), whereas placebo treatment had no statistically significant effects. Placebo-subtracted changes in body weight and abdominal circumference were −7 kg (P<0.02) and −5.2 cm (P<0.005), respectively. Glucose metabolism, lipid profiles, bone density, and physical exercise capacity did not change. Psychological testing did not reveal any changes during treatment.

Conclusion: Short-term, low dose aromatase inhibition in obesity-related hypogonadotropic hypogonadism normalizes serum testosterone and has beneficial effects on body composition.

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