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Hyperthyroidism caused by inappropriate thyrotropin hypersecretion: studies in patients with selective pituitary resistance to thyroid hormone

1982; American Medical Association; Volume: 142; Issue: 7 Linguagem: Inglês

10.1001/archinte.142.7.1283

1538-3679

Robert G. Spanheimer,

Thyroid Disorders and Treatments

• We have identified the condition of thyrotropin (thyroid-stimulating hormone [TSH])-induced hyperthyroidism secondary to selective pituitary insensitivity to thyroid hormone in three patients. Each patient was clinically hyperthyroid, with elevated serum levels of thyroxine (T 4 ) and triiodothyronine (T 3 ) and detectable levels of serum TSH before therapy. After therapy, each patient had notably elevated TSH levels at a time that peripheral levels of thyroid hormones were in the hyperthyroid range. Before and after therapy, serum levels of TSH were suppressed by therapy with liothyronine sodium and were stimulated by protirelin (thyrotropin-releasing hormone) both before and after liothyronine and dexamethasone treatment. Dexamethasone therapy decreased the levels of TSH, protirelin-stimulated TSH, and circulating T 4 and T 3 . Serum levels of glycoprotein α-subunit were 0.6 to 2.4 ng/ml, values considerably lower than found in patients with TSH-secreting pituitary tumors. We suggest that the frequency of TSH-induced hyperthyroidism secondary to pituitary insensitivity to thyroid hormone may be higher than presently indicated in the medical literature. ( Arch Intern Med 1982;142:1283-1286)