Increased plasma 5 alpha-androstane-3 alpha,17 beta-diol glucuronide concentration in clinically euthyroid women with suppressed plasma thyrotropin levels: further evidence for generalized tissue overexposure to thyroid hormones in these subjects.

It has been reported that plasma levels of 5 alpha-androstane-3 alpha,17 beta-diol glucuronide (ADG) are increased in thyrotoxic patients. The present study was carried out to determine whether in clinically euthyroid subjects with suppressed TSH levels, ADG plasma levels would also be increased, suggesting a more generalized tissue overexposure to thyroid hormones. The latter has been suggested from increased sex hormone-binding globulin levels (SHBG) in these subjects. ADG and SHBG levels were measured in a group of 20 euthyroid postmenopausal women, 20 postmenopausal women with clinically evident thyrotoxicosis, and 16 euthyroid postmenopausal women with suppressed TSH levels. The mean ADG level in the thyrotoxic group was 4 times the mean level in the control group, whereas in the group with isolated TSH suppression the mean level was about twice the level in the control group. As levels of dehydroepiandrosterone sulfate, the major precursor of plasma ADG, were not significantly increased in these subjects, these data suggest an increased conversion of dehydroepiandrosterone sulfate to ADG. Together with the increased SHBG levels observed in both thyrotoxic and euthyroid subjects with suppressed serum TSH concentrations, these data support the concept that the TSH-suppressed euthyroid subjects have generalized increased thyroid hormone effects on peripheral tissues.