A new marker in determining the relationship between the clinical outcomes of patients with sepsis and thyroid function tests: free triiodothyronine to free thyroxine ratio

Purpose: This study investigated the predictive value of thyroid hormones in septic patients. Materials and Methods: Our study was conducted in patients with sepsis in intensive care unit (ICU). Free triiodothyronine (fT3) and free thyroxine (fT4) levels taken at the time of hospitalization and at the 48th hours were measured and the fT3 / fT4 ratio was calculated. Calculated fT3 and fT4 change between first and 48th hours. Results: 192 patients with sepsis were included in the study. In non-survivor patients, first fT3 (1.60±0.57 ng/dL v.s. 2.01±0.41 ng/dL) and fT3 / fT4 ratio (1.34±0.88 v.s. 1.79±0.91) were found to be significantly lower than 48th hours fT3 (0.77±0.39 ng/dL v.s. 1.87±0.49 ng/dL) and fT3 / fT4 ratio (0.60±0.51 v.s. 1.66±1.21) survivors. It was found that the first fT3 levels (-0.83±0.45 v.s. -0.23±0.14) and fT3 / fT4 ratio (-0.73±0.62 v.s. -0.12±0.11) decreased significantly more at 48th hour in non-survivors than survivors. The 48th hours fT3 level and the change in fT3 between the first and 48th hour were found to be the most significant parameters for the mortality indicator. Conclusion: fT3 / fT4 ratio has predictive value for mortality in patients with sepsis in ICU. In addition, fT3 was found to be an indicator for mortality predictivity both at admission and at 48th hours.