How common is pituitary insufficiency after traumatic brain injury (TBI)?
The overall incidence of TBI in the United States has been estimated to be 538 cases per 100,000. The likelihood of pituitary insufficiency is directly related to the severity of the injury. Anterior pituitary deficiencies are more common acutely than 3 and 12 months afterward. In a study of patients with TBI, 76% had hormonal deficiencies in the acute phase; these persisted in only 13% and 11% of the patients after 3 and 12 months, respectively. GH and gonadotropin deficiencies are the two most common disturbances. The causative mechanism seems to be hemorrhagic infarction of the hypothalamus and/or the pituitary gland as a result of direct damage to these structures, increased intracranial pressure, hypoxia, or bleeding.