ObjectiveTo investigate the adrenocortical function in brain-dead patients, potential organ donors.DesignProspective study.SettingIntensive care units in two teaching hospitals.PatientsA total of 37 patients (28 men, nine women) with severe brain injury, having a mean age of 42 ± 18 yrs, were included in the study. Group A consisted of 20 brain-injured patients who did not deteriorate to brain death. Group B included 17 brain-injured patients who were brain dead; of these, ten patients developed brain death during ICU stay and seven patients were admitted to the ICU after clinical brain death.InterventionsIn all patients (group A and group B), a morning blood sample was obtained at admission to the ICU to determine baseline plasma cortisol. Subsequently, 1 &mgr;g of corticotropin (adrenocorticotropic hormone, Synacthen) was administered intravenously, and a blood sample was taken 30 mins after the injection. In group B patients who became brain dead while being treated in the ICU (n = 10), the same procedure was repeated the morning after the confirmation of brain death. Patients having a cortisol level of at least 18 &mgr;g/dL after the administration of adrenocorticotropic hormone were defined as responders.Measurements and Main ResultsAfter the occurrence of brain death, group B patients had significantly lower values for baseline (8.5 ± 6.2 vs. 17.0 ± 6.6 &mgr;g/dL,p< .001) and stimulated (16.9 ± 6.3 vs. 23.9 ± 5.7 &mgr;g/dL,p= .001) plasma cortisol compared with group A patients. Thirteen group B patients (76%) and two group A patients (10%) were nonresponders to adrenocorticotropic hormone (p< .001). In group B patients, baseline and stimulated cortisol concentrations were significantly related (r= .71,p= .001), whereas there was no correlation between baseline cortisol and the increment in cortisol (r= −.37,p= .15). Mean hormonal data of the ten brain-dead patients studied at admission in the ICU and after the occurrence of brain death were the following: baseline plasma cortisol (23.5 ± 11.4 vs. 6.8 ± 4.2 &mgr;g/dL,p= .003) and stimulated serum cortisol (28.8 ± 9.9 vs. 16.3 ± 4.3 &mgr;g/dL,p= .008).ConclusionsAdrenal cortisol secretion after dynamic stimulation is deficient in a substantial proportion of brain-dead potential organ donors.