BACKGROUND: Traumatic brain injury (TBI) results in a hypermetabolic and hypercatabolic status in which adequate nutrition support is essential to improve clinical outcome. The endocrine system of a patient with TBI is also affected and may play a critical role in either the metabolic or the immunologic response to the trauma. In the present study, the effect of standard, delayed enteral feeding (DEF), compared with early (within 24-48 hours) enteral feeding (EEF), on the endocrine function of patients with TBI was investigated.METHODS: This comparative, prospective, open-labeled, randomized study included TBI patients admitted to the intensive care unit (ICU). Injury severity was assessed by the Glasgow Coma Scale and predicted mortality by the Acute Physiology and Chronic Health Evaluation II. Twenty-five patients received DEF and 34 patients received EEF. The effect of the onset of nutrition on pituitary, thyroidal, gonadal, and adrenal function was investigated on days 6 and 12 after admission to the hospital.RESULTS: Levels of thyroid-stimulating hormone, free triiodothyronine, free thyroxine, and testosterone (in males) of DEF patients declined in comparison to levels of the day of admission to the ICU. The decrease of hormonal values was less pronounced in the EEF group. Cortisol concentrations rose in the DEF group; a lesser hormonal change was found in the EEF group. Deaths during the study for the DEF group and EEF group were 2 and 3, respectively.CONCLUSIONS: EEF may exert beneficial effects on the hormonal profile of TBI patients, possibly contributing to a better clinical outcome in this patient group.