Fatigue after TBI: Association with neuroendocrine abnormalities

Objective: Evaluate the association between neuroendocrine findings and fatigue after traumatic brain injury (TBI) Research design: Prospective, observational. Methods and procedures: Sixty- four individuals at least 1 year post-TBI underwent neuroendocrine testing including thyroid, adrenal, gonadal axes and growth hormone (GH) after glucagon stimulation with assessment of fatigue using the Global Fatigue Index ( GFI) and the Fatigue Severity Scale (FSS). Main outcomes and results: GFI and FSS scores were significantly higher within this sample compared to published control data. At least one pituitary axis was abnormal in 90% of participants. Higher GH levels were significantly associated with higher FSS scores. There was a noted trend between lower basal cortisol and higher scores on both the FSS and GFI. Conclusions: The association between higher GH levels and greater fatigue contradicted the prevailing hypothesis that postacute TBI fatigue is associated with GH deficiency. The association between lower basal cortisol and greater fatigue was in the expected direction. While no other trends were noted, the fatigue derived from neuroendocrine abnormalities alone may be masked by fatigue induced by other factors commonly experienced following TBI. Given the high prevalence of pituitary abnormalities, screening for hypopituitarism after TBI is a reasonable recommendation. The contribution of GH deficiency to diminished quality of life post- TBI remains unclear.