Correlation of Thyroid Hormones in the Prognosis of Critically Ill Patients

Abstract

Objective: Non-thyroidal illness syndrome (NTIS) is associated with outcomes in Intensive Care Unit(ICU) patients. The objectives of the study were to assess the prognostic value of complete thyroid profile in critically ill patients and to determine the effect of thyroid hormone level in predicting mortality when used along with acute physiology and chronic health evaluation (APACHE) II score.
Methods: The observational study was conducted at a tertiary care centre in Kolhapur, India. Critically ill adult patients admitted to intensive care units with APACHE II >10 was included(n=50). Relevant clinical investigations along with thyroid profile evaluation was carried out and APACHE II was calculated.  Baseline characteristics of patients were compared.  Performance of variables in predicting mortality was analysed. Correlation of APACHE II score with thyroid was also assessed in R software v-3.6.1.
Results: The survival rate at ICU discharge was 54%. Mean T3, FT3, and T4 levels were significantly low in non-survivors(p=0.006758, p=0.0245 and p=0.00070 respectively).  Mean APACHE II score was significantly high in non- survivor(p=2.94E^-06). APACHE II score was significantly associated with the severity of disease (p=0.0235). APACHE II scores and FT3 were better predictors of mortality compared to other thyroid hormones (AUC =0.8519±0.0535). FT3 showed high correlation with APACHE II score(r=-0.4083; p=0.0032). Inclusion of thyroid hormone levels with APACHE II scores improved the prediction of mortality in critically ill patients by 5.63%.
Conclusion: Among thyroid hormones, FT3 is a better predictor of mortality. Use of thyroid hormone levels in conjunction with APACHE II scores improves the prognostication.