Neuroendocrine derangements after traumatic brain injury (TBI) have received increasing recognition in recent years. Marked changes of the hypothalamo-pituitary axis have been documented in the acute phase of TBI with as many as 80% of patients showing evidence of gonadotropin deficiency, 18% of growth hormone deficiency, 16% of corticotrophin deficiency and 40% of patients demonstrating vasopressin abnormalities. Longitudinal prospective studies have shown that some of the early abnormalities are transient, while new endocrine dysfunction becomes apparent in the post acute phase....