NEW ORLEANS – A head injury can cause immediate hypopituitarism that may last for up to 12 months and set the stage for new-onset pituitary deficiencies during that time, researchers said at the annual meeting of the Endocrine Society.
Neuroendocrine abnormalities are common in the acute phase of a traumatic brain injury (TBI), said Amar Agha, M.D., of Beaumont Hospital, Dublin, Ireland. Dr. Agha tested pituitary function in 50 TBI patients and 31 age-matched healthy controls and found that almost all patients had some form of pituitary dysfunction in the first 2 weeks after a mild or moderate brain injury.
All subjects had a glucagon stimulation test. For TBI patients, the test was performed within 12 days of the injury. Of the injured patients, 16% had subnormal peak cortisol responses and 18% had subnormal growth hormone responses; these findings were unrelated to age, body mass index, initial Glasgow Coma Score (GCS), or levels of insulinlike growth factor I.
A gonadotropin deficiency unrelated to the presence of hyperprolactinemia was seen in 80% of the injured patients. In males, low serum testosterone concentrations were associated with low (more severe) GCS scores.
Hyperprolactinemia was present in 52% of the patients. High serum prolactin levels were associated with low GCS scores. Cranial diabetes insipidus was present in 26% of the patients, and 14% had inappropriate antidiuretic hormone secretion.
“Recognition of post-head injury hypopituitarism is important, as undiagnosed hormone deficiencies may have serious consequences,” Dr. Agha said. “Appropriate and timely hormone replacement in affected patients may accelerate recovery and improve prognosis.”
Whether these abnormalities are permanent remains unclear, Dr. Agha said. But even though some pituitary dysfunction resulting from traumatic brain injury is transient, total hypopituitarism diagnosed in the early postinjury period persists after a full year of recovery, said Gianluca Aimaretti, M.D., of the University of Turin (Italy).
Dr. Aimaretti followed 47 TBI patients for 1 year, testing their pituitary function at 3 months and 12 months post injury. The patients' average age was 37 years; 33 patients were male.
At the 3-month evaluation, some degree of hypopituitarism was present in 40.4% of the patients, including 8.5% with total dysfunction, 6.3% with multiple deficits, and 25.6% with isolated deficits.
At 12 months, only 27.6% showed some degree of hypopituitarism, but all of the patients with early total hypopituitarism maintained that diagnosis. Also, about 4% of the patients whose pituitary function was normal at 3 months had developed isolated deficits (either secondary adrenal or secondary gonadal insufficiency).