A case of isolated thyrotropin deficiency with Cushing's syndrome

The first case of isolated thyrotropin (TSH) deficiency with Cushing's syndrome was reported. A 46-year-old female was admitted to our hospital because of fatigability, puffy eye-lids, leg edema and petechia. She was treated with thyroid hormone. A low free triiodothyronine continued. Serum TSH was undetectable and serum thyrotropin releasing hormone (TRH) was elevated. No response of serum TSH and normal response of serum prolactin after administration of exogenous TRH suggested the abnormalities of anterior pituitary gland. The secretion of growth hormone and gonadotropin were intact, but the secretion of adrenocorticotropic hormone (ACTH) was impaired. A high level of serum cortisol, no response of serum ACTH by metyrapone test and a tumor mass of abdomen detected by computed tomography led to the diagnosis of Cushing's syndrome. Histological examination of the tumor revealed adrenal adenoma. Twenty two months after the surgery, serum ACTH level was normalized, but the secretion of serum TSH to exogenous TRH was still absent. The results indicated that hypothyroidism in our patient was due to isolated TSH deficiency.