BACKGROUND:Prognostic value of cortisol and thyroid function tests (TFTs) has previously been evaluated in medical ICUs. We aimed to evaluate prognostic efficacy of cortisol and TFTs in critical y il poisoned patients admitted to toxicology intensive care unit (ICU). METHODS:In a prospective study of consecutively enrolled subjects admitted to the toxicology ICU, lab analyses included TFTs (total T3 and T4 as well as TSH) and cortisol levels drawn between 8 am–10 am during period of the first 24 hours post-ingestion/exposure. Simplified Acute Physiology Score II (SAPS II) and Acute Physiology and Chronic Health Evaluation II (APACHE II) were recorded. All scores were compared to detect the best prognostic factor. Type of poisoning was also included. RESULTS:In 200 patients evaluated, 129 were male and mean age was 31 years. In general, SAPS II, T4, and cortisol could prognosticate death. After regression analysis, only cortisol had such efficacy (P=0.04; OR=1.06; 95％CI=1.05–1.08; cut-off=42 μg/dL; sensitivity=70％; specificity=82％). Between aluminium phosphide (ALP)- and non ALP-poisoned patients, level of consciousness, mean arterial pressure, and cortisol level could prognosticate death in ALP poisoning (all Ps<0.001 in both uni and multivariate analyses). Median (interquartile range; IQR) GCS was 7 (6, 10) and 15 (8, 15) in non-ALP and ALP-poisoned patients (P<0.003). SAPS II and APACHE II could not prognosticate death at all. CONCLUSION:Cortisol best prognosticated outcomes for subjects admitted to the toxicology ICU. Its level is higher in ALP-poisoned patients probably due to the higher stress while they remain conscious till the final stages of toxicity and are aware of deterioration of their clinical condition or may be due to their significantly lower blood pressures.