Background: Euthyroid unwell syndrome (ESS) or nonthyroidal illness syndrome during critical illness episodes in the medical intensive care unit. Aberrant thyroid function assays are implemented. This study aimed to examine the correlation between mortality and prognosis and the prevalence of ESS in critical cases admitted to the intensive care unit. Methods: This observational cross-sectional study included 100 patients admitted with different causes of both sex and between 16 and 80 years. Assessment of critical illness scores were APACHE II score, SOFA score and Glasgow coma scale. Results: The APACHE II score was significantly worse in the ESS group compared to the no ESS group. The APACHE II score was significantly worse in types 3 and 4 compared to types 1 and 2. Type 2, Type 3, and Type 4 have significantly higher mortality rates, with Type 3 and Type 4 showing a 100% mortality rate. Conclusion: ESS with an incidence rate of 30, was significantly associated with higher mortality, worse APACHE II scores, and longer ICU stays, particularly in patients with Type 3 and Type 4 ESS, both of which exhibited a 100% mortality rate. Lower thyroid stimulating hormone and free T3 levels and higher free T4 levels were characteristic of the ESS group. The study also found a significant association between ESS and specific admission indications such as acute kidney injury, pneumonia, and decompensated chronic liver disease, with these conditions more prevalent in the more severe ESS subtypes |
