Central Hypothyroidism and Impaired Growth Hormone Secretion Due to Subclinical Cushing's Syndrome: A Case Report

A 34-year-old Chinese woman presenting with general fatigue was found to have central hypothyroidism and low-normal insulin-like growth factor 1 (IGF-1). Although she had no cushingoid features, her adrenocorticotropic hormone levels were suppressed, while her serum cortisol levels were normal. Cortisol secretion was not suppressed following a 1-mg dexamethasone suppression test, and computed tomography revealed a left adrenal tumor. After adrenalectomy, her thyroid function, growth hormone (GH) secretion, and IGF-1 levels were normalized. A histopathological examination confirmed adrenocortical adenoma. This case demonstrates that mild autonomous cortisol secretion can impair GH secretion and cause central hypothyroidism even in the absence of any overt cushingoid features.