Hypopituitarism after traumatic brain injury.

Traumatic brain injury (TBI) is one of the main causes of death and disability in young adults, with consequences ranging from physical disabilities to long-term cognitive, behavioural, psychological and social defects. Post-traumatic hypopituitarism (PTHP) was recognized more than 80 years ago, but it was thought to be a rare occurrence. Recently, clinical evidence has demonstrated that TBI may frequently cause hypothalamic-pituitary dysfunction, probably contributing to a delayed or hampered recovery from TBI. Changes in pituitary hormone secretion may be observed during the acute phase post-TBI, representing part of the acute adaptive response to the injury. Moreover, diminished pituitary hormone secretion, caused by damage to the pituitary and/or hypothalamus, may occur at any time after TBI. PTHP is observed in about 40% of patients with a history of TBI, presenting as an isolated deficiency in most cases, and more rarely as complete pituitary failure. The most common alterations appear to be gonadotropin and somatotropin deficiency, followed by corticotropin and thyrotropin deficiency. Hyper- or hypoprolactinemia may also be present. Diabetes insipidus may be frequent in the early, acute phase post-TBI, but it is rarely permanent. Severity of TBI seems to be an important risk factor for developing PTHP; however, PTHP can also manifest after mild TBI. Accurate evaluation and long-term follow-up of all TBI patients are necessary in order to detect the occurrence of PTHP, regardless of clinical evidence for pituitary dysfunction. In order to improve outcome and quality of life of TBI patients, an adequate replacement therapy is of paramount importance.