[TeBG and thyrotoxicosis in the hot thyroid nodule].

The binding capacity of serum TeBG (testosterone-estradiol binding globulin), the plasma concentrations of thyroid hormones and the TSH response to TRF (200 micrograms i.v.) have been measured in female patients with a solitary autonomously functioning thyroid nodule (n = 26) or with a cold thyroid nodule (n = 20). It was found that TeBG was higher than the upper limit for normal (1.77 micrograms/dl) in the patients (n = 10) with increased serum concentrations of thyroid hormones and in 5 patients among 16 with normal thyroid hormone levels. After surgical removal of the nodule, the increased TeBG levels fell down within the normal, while the response of TSH to TRF which was suppressed before surgery, was recovered. In patients with a cold nodule, the administration of dl-Thyroxine (200-300 micrograms/daily) suppressed the response of TSH to TRF and increased slightly TeBG from 0.97 +/- 0.08 to 1.29 +/- 0.10 micrograms/dl (p less than 0.05) with a value higher than 1.77 micrograms/dl in 5. These data suggested that the pituitary secretion of TSH and the liver production of TeBG have a different threshold of sensitivity to thyroid hormones action. It is proposed that the measure of TeBG is a tool for the diagnosis of thyrotoxicosis in patients with autonomous thyroid nodules.