The concentration and binding of thyroxine in the serum of patients with the testicular feminization syndrome: observations on the effects of ethinyl estradiol and norethandrolone.

Abstract

In 6 castrated patients with the complete testicular feminization syndrome, values for total and free thyroxine (T4) concentration in serum, as well as the T4-binding capacities of thyroxine binding globulin (TBG) and thyroxine binding prealbumin (TBPA), were within normal limits. As expected, patients with TFS responded to 0.02 mg ethinyl estradiol daily with increases in both the T4-binding capacity of TBG and the concentration of serum T4 and a decrease in the proportion of free T4. The magnitude of the responses was similar to that obtained in 3 normal patients given the same dose of ethinyl estradiol. In a normal patient receiving ethinyl estradiol, norethandrolone (40 mg daily) produced the expected decrease in TBG and total T4 concentration and increase in the percentage of free T4. In contrast, in 4 patients with TFS receiving ethinyl estradiol, norethandrolone did not influence TBG, total serum T4 concentration, or the proportion of free T4. A similar lack of effect of norethandrolone on TBG was ...