Recombinant Human Thyrotropin Is a Potent Stimulator of Thyroid Function in Normal Subjects

Recombinant human TSH (rhTSH) is known to stimulate 131I uptake and thyroglobulin (Tg) release from the postoperative remnant and metastases in thyroid cancer patients, but its effects on serum thyroid hormone and Tg concentrations in normal subjects have not been reported. Before using rhTSH in the management of thyroid disorders other than cancer, the thyroid response to rhTSH in normal subjects must be assessed. Six subjects, two men and four women, without evidence of thyroid disease, including normal serum free T4 index and TSH concentrations and negative tests for antithyroid peroxidase and Tg, were studied. Each received 0.1 mg rhTSH, im, 11% of the lowest dose that has been administered to thyroid cancer patients. Blood was obtained before; 2, 4, and 8 h after; and 1, 2, 3, 4, 7, and about 3 weeks after rhTSH administration. Serum TSH significantly increased at 2 h (mean ± se, 2.4 ± 0.9 to 40.7 ± 7.4 mU/mL), peaked at 4 h (50.9 ± 9.3), remained significantly elevated for 1 day, and was significant...