Adrenal function testing in patients with septic shock

Introduction Adrenal failure (AF) is associated with increased mortality in septic patients. Nonetheless, there is no agreement regarding the best diagnostic criteria for AF. We compared the diagnosis of AF considering different baseline total cortisol cutoff values and Delta max values after low ( 1 mu g) and high ( 249 mu g) doses of corticotropin, we analyzed the impact of serum albumin on AF identification and we correlated laboratorial AF with norepinephrine removal. Methods A prospective noninterventional study was performed in an intensive care unit from May 2002 to May 2005, including septic shock patients over 18 years old without previous steroid usage. After measurement of serum albumin and baseline total cortisol, the patients were sequentially submitted to 1 mu g and 249 mu g corticotropin tests with a 60-minute interval between doses. Post-stimuli cortisol levels were drawn 60 minutes after each test ( cortisol 60 and cortisol 120). The cortisol 60 and cortisol 120 values minus baseline were called Delta max(1) and Delta max(249), respectively. Adrenal failure was defined as Delta max(249) <= 9 mu g/dl or baseline cortisol <= 10 mu g/dl. Other baseline cortisol cutoff values referred to as AF in other studies (<= 15, <= 20, <= 25 and <= 34 mu g/dl) were compared with Delta max(249) <= 9 mu g/dl and serum albumin influence. Norepinephrine removal was compared with the baseline cortisol values and Delta max(249) values. Results We enrolled 102 patients ( 43 male). AF was diagnosed in 22.5% (23/102). Patients with albumin <= 2.5 g/dl presented a lower baseline total cortisol level (15.5 mu g/dl vs 22.4 mu g/dl, P = 0.04) and a higher frequency of baseline cortisol <= 25 mu g/dl (84% vs 58.3%, P = 0.05) than those with albumin > 2.5 g/dl. The Delta max(249) levels and Delta max(249) <= 9, however, were not affected by serum albumin (14.5 mu g/dl vs 18.8 mu g/dl, P = 0.48 and 24% vs 25%, P = 1.0). Baseline cortisol = 23.6 mu g/dl was the most accurate diagnostic threshold to determine norepinephrine removal according to the receiver operating characteristic curve. Conclusion AF was identified in 22.5% of the studied population. Since Delta max(249) <= 9 mu g/dl results were not affected by serum albumin and since the baseline serum total cortisol varied directly with albumin levels, we propose that Delta max(249) <= 9 mu g/dl, which means Delta max after high corticotropin dose may be a better option for AF diagnosis whenever measurement of free cortisol is not available. Baseline cortisol <= 23.6 mu g/dl was the best value for predicting norepinephrine removal in patients without corticosteroid treatment.