To investigate cortisol reserve in head trauma, 35 consecutive patients (30 men) with a mean age of 36 ± 16 years were studied 5–60 days after physical injury. Patients were enrolled in the study within a few days before ICU discharge. First, a morning blood sample was obtained to measure baseline cortisol, and ACTH plasma levels. Subsequently, 1 μg synthetic ACTH was injected intravenously and, 30 min later, a second blood sample was drawn to determine stimulated plasma cortisol. Patients having stimulated cortisol levels below 18 μg/dl were defined as nonresponders to the low-dose stimulation test (LDST). Mean (± SD) values for ACTH, baseline, and stimulated cortisol concentrations were 49 ± 27 pg/ml, 19.7 ± 5.5 μg/dl and 23.6 ± 6.7 μg/dl, respectively. Six of the 35 patients (17%) failed the LDST. Nonresponders were similar to responders with regard to age, gender, and severity of head injury. However, nonresponders more frequently required vasopressors (6/6 vs 14/29, P = 0.02) and for a longer time interval (median, 293 hours vs 24 hours, P = 0.01) to maintain haemodynamic stability compared with responders to the LDST.

In conclusion, adrenal cortisol secretion following dynamic stimulation is deficient in a subset of head injury patients; this condition is associated with vasopressor dependency.