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Hypothalamic-pituitary-testicular axis and seminal parameters in hyperthyroid males
M Abalovich1, O Levalle, R Hermes
1División Endocrinology, Hospital Carlos Durand, Buenos Aires, Argentina. levalle@pure.com.ar
Thyroid : Official Journal of the American Thyroid Association
|October 19, 1999
Summary
Hyperthyroidism significantly impacts male reproductive health, affecting the hypothalamic-pituitary-testicular axis and sperm quality. Restoring thyroid function (euthyroidism) largely reverses these detrimental effects on male fertility.
Area of Science:
- Endocrinology
- Reproductive Medicine
- Andrology
Background:
- Limited data exists on thyroid dysfunction's impact on male reproduction compared to female reproduction.
- Graves' disease, a common cause of hyperthyroidism, can potentially disrupt hormonal balance and reproductive function in men.
Purpose of the Study:
- To investigate the effects of hyperthyroidism on the hypothalamic-pituitary-testicular axis in men.
- To assess the impact of hyperthyroidism on spermogram parameters and male sexual function.
- To evaluate the reversibility of these effects after achieving euthyroidism.
Main Methods:
- Studied 25 male patients with active Graves' disease, measuring various hormones (LH, FSH, PRL, T, E2, 17-OHP, SHBG, bioavailable T) before and after stimulation tests (GnRH/TRH, HCG).
- Assessed spermogram parameters according to WHO criteria in 21 patients.
- Re-evaluated hormonal and seminal parameters in six patients after achieving euthyroidism.
Main Results:
- Hyperthyroid patients exhibited altered LH and PRL responses to GnRH/TRH stimulation.
- Significantly higher basal levels of testosterone, estradiol, 17-OHP, and SHBG were observed in patients compared to controls.
- Reduced testosterone and 17-OHP response to HCG stimulation and lower bioavailable testosterone were noted.
- High incidence of abnormal semen parameters, including asthenospermia (85.7%) and hypospermia (61.9%).
- Euthyroidism led to normalization of 85% of seminal alterations.
Conclusions:
- Hyperthyroidism causes significant disruptions in the gonadotropic and prolactin axes.
- Graves' disease dramatically impairs male spermatic function, leading to various semen abnormalities.
- Bioavailable testosterone measurement is crucial for identifying hypoandrogenism in hyperthyroid men.
- Achieving euthyroidism is associated with substantial recovery of semen parameters, suggesting the reversibility of hyperthyroidism-induced infertility.