OBJECT: The aim of the study was to evaluate the early changes in pituitary 
hormone levels after severe traumatic brain injury (sTBI) and compare hormone 
levels to basic neuro-intensive care data, a systematic scoring of the 
CT-findings and to evaluate whether hormone changes are related to outcome.
METHODS: Prospective study, including consecutive patients, 15-70 years, with 
sTBI, Glasgow Coma Scale (GCS) score ≤ 8, initial cerebral perfusion pressure > 
10 mm Hg, and arrival to our level one trauma university hospital within 24 
hours after head trauma (n = 48). Serum samples were collected in the morning 
(08-10 am) day 1 and day 4 after sTBI for analysis of cortisol, growth hormone 
(GH), prolactin, insulin-like growth factor 1 (IGF-1), thyroid-stimulating 
hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), follicular 
stimulating hormone (FSH), luteinizing hormone (LH), testosterone and sex 
hormone-binding globulin (SHBG) (men). Serum for cortisol and GH was also 
obtained in the evening (17-19 pm) at day 1 and day 4. The first CT of the brain 
was classified according to Marshall. Independent staff evaluated outcome at 3 
months using GOS-E.
RESULTS: Profound changes were found for most pituitary-dependent hormones in 
the acute phase after sTBI, i.e. low levels of thyroid hormones, strong 
suppression of the pituitary-gonadal axis and increased levels of prolactin. The 
main findings of this study were: 1) A large proportion (54% day 1 and 70% day 
4) of the patients showed morning s-cortisol levels below the proposed cut-off 
levels for critical illness related corticosteroid insufficiency (CIRCI), i.e. 
<276 nmol/L (=10 ug/dL), 2) Low s-cortisol was not associated with higher 
mortality or worse outcome at 3 months, 3) There was a significant association 
between early (day 1) and strong suppression of the pituitary-gonadal axis and 
improved survival and favorable functional outcome 3 months after sTBI, 4) 
Significantly lower levels of fT3 and TSH at day 4 in patients with a poor 
outcome at 3 months. 5) A higher Marshall CT score was associated with higher 
day 1 LH/FSH- and lower day 4 TSH levels 6) In general no significant 
correlation between GCS, ICP or CPP and hormone levels were detected. Only 
ICPmax and LH day 1 in men was significantly correlated.
CONCLUSION: Profound dynamic changes in hormone levels are found in the acute 
phase of sTBI. This is consistent with previous findings in different groups of 
critically ill patients, most of which are likely to be attributed to 
physiological adaptation to acute illness. Low cortisol levels were a common 
finding, and not associated with unfavorable outcome. A retained ability to a 
dynamic hormonal response, i.e. fast and strong suppression of the 
pituitary-gonadal axis (day 1) and ability to restore activity in the 
pituitary-thyroid axis (day 4) was associated with less severe injury according 
to CT-findings and favorable outcome.