Low triiodothyronine serum levels as a predictor of poor prognosis in burn patients

Objective Euthyroid sick syndrome is a common finding in critically ill patients with nonthyroidal illness, characterized by low serum levels of free triiodothyronine (fT3) with a peculiar increase in reverse T3 (rT3) and normal-to-low free thyroxine (fT4) as well as thyroid-stimulating hormone (TSH) levels. This condition has been proposed as a prognostic factor of worse outcome in critically ill patients, while no conclusive data are available in burns. Methods Since thyroid function testing is contained in our baseline laboratory tests at admission, we retrospectively evaluated fT3, fT4 and TSH in 295 consecutive burn patients admitted to the Burn Center of Turin from January 2002 to December 2006, comparing hormone levels in survivors and non-survivors. Results fT3 and TSH levels were significantly lower (p ≤ 0.0002) in non-survivors compared to survivors, while no significant difference between the two populations was found in fT4 concentrations. Excluding from the study 20 patients who received dopamine administration for more than 21 h, serum fT3 levels fell further still (p = 0.0003). In addition, fT3 concentrations showed a significant correlation with burn severity expressed by the Roi score (Spearmanʹs correlation coefficient −0.37 with p < 0.00001). Conclusion Low fT3 levels are associated with poor outcome in burn patients. Hence, fT3 measurement could be proposed as a strong and cost-effective tool of poor prognosis.