TSH unresponsiveness, a case report.

A patient with congenital primary hypothyroidism is presented. His thyroid gland had a normal uptake of radioiodine which was independent of endogenous or exogenous TSH, sympathetic B-receptor blockade or prostaglandin inhibition. Infusion of dibuturyl-cyclic AMP increased the uptake of radioiodine and stimulated release of protein bound 131I. He had no goitre even when he did not receive thyroxine, but thyroid histology showed evidence of active epithelium in the presence of adequate substitution with thyroxine. We assume that some unknown factor other than TSH stimulates part of the glandular function in this patient, without leading to adequate formation and release of thyroid hormone.