Endocrine studies, using the four
hypothalamic releasing hormones, gonadotrophin releasing
hormone,
thyrotrophin releasing
hormone,
corticotrophin releasing
hormone and
growth hormone releasing hormone, were performed in 33 males after admission with a major
head injury. The test was repeated 7 days later in all 33 patients and after 3-6 months in 21 patients. All patients had a period of unconsciousness followed by post-traumatic
amnesia of greater than 24 h. The results obtained from investigating the gonadal axis are reported in this paper. The levels of total and free
testosterone, basal FSH and basal LH fell significantly during the first 3 days after injury, when the LH and FSH responses to
GnRH achieved their highest peak levels. This
hormone pattern has not previously been reported in the gonadal axis and may be a consequence of hypothalamic dysfunction. The severity of the injury was negatively correlated to the
testosterone concentration on admission and to the basal and peak FSH concentrations 1 week later. Persistent
hypogonadism was found in five of the 21 patients retested after 3-6 months, with low
testosterone concentrations and three continued to have an exaggerated LH response to
GnRH. Thus major
head injury frequently results in
hypogonadism shortly after injury, with an increased gonadotrophin response to
GnRH. In addition, a substantial minority of patients continue to be hypogonadal after 3-6 months. In view of these findings we strongly suggest that all patients should be endocrinologically assessed at intervals following severe
head injury.