Evidence that mouse thyroid stimulator does not stimulate the human thyroid gland

Thyroid 131I uptake and human thyroid stimulator (HTS) level were measured in 20 untreated thyrotoxic patients who also showed mouse thyroid stimulator (MTS) ACtivity. The correlation between thyroid uptake and HTS level was highly significant (P less than 0-005), the coefficient, r, being 0-66, comparable with the value 0-68 obtained in a previous study of patients not showing MTS. Thus, the presence of widely varying amounts of MTS does not impair the close correlation existing between HTS level and thyroid 131I uptake in thyrotoxic people. There was no correlation between MTS level and thyroid 131I uptake (r = 0-11, n.s.). It is concluded that MTS, a potent stimulator of the thyroid glands of mice, guinea pigs and monkeys, does not stimulate the human thyroid gland.