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 Δmax values after low (1 μg) and high (249 μg) 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 μg and 249 μg 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 Δmax(1 )and Δmax(249), respectively. Adrenal failure was defined as Δmax(249 )≤ 9 μg/dl or baseline cortisol ≤ 10 μg/dl. Other baseline cortisol cutoff values referred to as AF in other studies (≤15, ≤20, ≤25 and ≤34 μg/dl) were compared with Δmax(249 )≤ 9 μg/dl and serum albumin influence. Norepinephrine removal was compared with the baseline cortisol values and Δmax(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 μg/dl vs 22.4 μg/dl, P = 0.04) and a higher frequency of baseline cortisol ≤25 μg/dl (84% vs 58.3%, P = 0.05) than those with albumin > 2.5 g/dl. The Δmax(249 )levels and Δmax(249 )≤ 9, however, were not affected by serum albumin (14.5 μg/dl vs 18.8 μg/dl, P = 0.48 and 24% vs 25%, P = 1.0). Baseline cortisol ≤ 23.6 μg/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 Δmax(249 )≤ 9 μg/dl results were not affected by serum albumin and since the baseline serum total cortisol varied directly with albumin levels, we propose that Δmax(249 )≤ 9 μg/dl, which means Δmax after high corticotropin dose may be a better option for AF diagnosis whenever measurement of free cortisol is not available. Baseline cortisol ≤23.6 μg/dl was the best value for predicting norepinephrine removal in patients without corticosteroid treatment.