Context: Thyroid hormones have a dramatic effect on human behavior. However, their role on sexual behavior and performance has seldom been investigated in men.
Objective: The objective of this study was to evaluate the prevalence of sexual dysfunctions in patients with hyper- and hypothyroidism and their resolution after normalization of thyroid hormone levels.
Design and setting: We conducted a multicenter prospective study at endocrinology and andrology clinics in university hospitals.
Patients: The study included 48 adult men, 34 with hyperthyroidism and 14 with hypothyroidism.
Main outcome measures: Subjects were screened for hypoactive sexual desire (HSD), erectile dysfunction (ED), premature ejaculation (PE), and delayed ejaculation (DE) on presentation and 8-16 wk after recovery from the thyroid hormone disorder.
Results: In hyperthyroid men, HSD, DE, PE, and ED prevalence was 17.6, 2.9, 50, and 14.7%, whereas in hypothyroid men, the prevalence of HSD, DE, and ED was 64.3% and of PE was 7.1%. After thyroid hormone normalization in hyperthyroid subjects, PE prevalence fell from 50 to 15%, whereas DE was improved in half of the treated hypothyroid men. Significant changes were found in the subdomains of the International Index of Erectile Function; ejaculation latency time doubled after treatment of hyperthyroidism (from 2.4 +/- 2.1 to 4.0 +/- 2.0 min), whereas for hypothyroid men it declined significantly, from 21.8 +/- 10.9 to 7.4 +/- 7.2 (P < 0.01 for both). TSH and thyroid hormone levels normalized rapidly after treatment, and changes in circulating sex steroids partially reflected the changes in SHBG levels.
Conclusions: In summary, most patients with thyroid hormone disorders experience some sexual dysfunctions, which can be reversed by normalizing thyroid hormone levels. Despite the associated changes in sex hormone levels, the high prevalence of ejaculatory disorders and their prompt reversibility suggest a direct involvement of thyroid hormones in the physiology of ejaculation.