Effect of Adequate Thyroid Hormone Replacement on the Hypothalamo-Pituitary-Gonadal Axis in Premenopausal Women with Primary Hypothyroidism.

Background: While the effects of thyroxine (T) replacement on improving gonadal function in hypothyroid men has been well documented, the same has not been adequately studied in hypothyroid premenopausal women.

Methodology: Premenopausal women with overt hypothyroidism (thyroid-stimulating hormone [TSH] > 15 IU/L) were tested in the early follicular phase of their natural menstrual cycles or after a progesterone challenge for gonadotropins, estradiol (E), and prolactin (PRL). They were then treated adequately with T replacement and retested under similar circumstances for the same parameters ≥2 months after the restoration of euthyroidism.