Thyrotropin-releasing hormone provocative release of prolactin and thyrotropin in acute head injury.

The thyrotropin-releasing hormone (TRH) test was performed in 30 patients soon after trauma to evaluate the effects of acute head injury on hypothalamohypophyseal functions. Plasma prolactin (PRL) and thyrotropin (TSH) were measured before and after TRH loading. The basal level of the plasma PRL was elevated in patients with severe head injuries compared to those without. The patients with severe head injuries exhibited a lower PRL response to TRH. On the other hand, the basal level of plasma TSH and its response to TRH remained within the normal range. These findings suggest that the PRL data in the TRH test are significant in evaluating the severity of head injuries.