Sex steroid replacement in post-menopausal women: effects on thyroid hormone status

We have measured serum thyroxine (T4), triidothyronine (T3), thyroid-stimulating hormone (TSH) free thyroxine (FT4) and thyroxine-binding globulin (TBG) levels in a total of 5 post-menopausal women who were receiving oestrogen alone (Premarin, n = 19), progestogen alone (Primolut-N, n = 12), a combination of oestrogen and progestogen (Prempak C, n = 14) or no treatment (control group, n = 12). No differences were observed between the Premarin and Prempak C groups; both exhibited elevated T4 and TBG levels, although free thyroxin (FT4) and T4/TBG concentrations were normal relative to those in the control group. The Primolut-N subjects showed subnormal T3 and FT4 levels relative to the controls. It was concluded that it is not possible to make general statements regarding the effects of sex steroids on FT4 levels.