Role of sex-hormone-binding globulin in hormonal changes and amenorrhoea in thyrotoxic women.

Plasma levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), oestrogen, testosterone and sex-hormone-binding globulin (SHBG) were determined in 15 thyrotoxic women in the reproductive age before and after treatment with carbimazole. The levels of these hormones and SHBG were compared with those of 12 euthyroid healthy female volunteers of comparable age and parity. Plasma gonadotrophins (LH and FSH), oestrogen, testosterone and SHBG were all markedly elevated in thyrotoxic subjects but became normal when the euthyroid state and normal menstruation were restored after treatment. From the results a hypothesis is suggested that related the hormonal disturbance primarily to a thyroid hormone-induced rise in SHBG levels.