Pituitary secretion of alpha and beta subunits of thyroid-stimulating hormone (TSH) in nephropathic cystinosis

In 13 children with nephropathic cystinosis but without clinical features of hyperthyroidism or hypothyroidism, mean circulating thyroid-stimulating hormone (TSH) levels were high, while concentrations of thyroid hormones were either increased or in the high-normal range compared with those in age-matched, healthy control subjects. Serum TSHalpha was significantly elevated and was above the normal range in 7 of 12 patients; in contrast, only 2 of 13 patients had minimally increased TSHbeta levels. Patients with cystinosis appear to have pituitary resistance to thyroid hormones, and the increase in serum TSH is often associated with high levels of TSHalpha .