Euthyroid Sick Syndrome as a Predictor of Hospital Stay in Pediatric Diabetic Ketoacidosis

Background: Euthyroid sick syndrome (ESS) is commonly diagnosed in children during acute metabolic stress such as diabetic ketoacidosis (DKA). Nevertheless, the association of ESS with clinical outcomes has not been fully established. This study aimed to address the association between ESS and duration of hospital stay among pediatric patients presenting with DKA. Methods: This retrospective cohort study included 176 children admitted with confirmed DKA. Baseline clinical, biochemical, and outcome data, including complications and time to discharge, were collected. Kaplan-Meier survival analysis and Cox proportional hazards regression models were used to assess factors associated with duration of hospital stay. Results: Children were classified based on thyroid function tests at admission into ESS (n = 112, 63.6%) and non-ESS (n = 64, 36.4%). Children with ESS were younger [median age 10.0 (6.5-13.5) years vs. 14.0 (11.5-16.0) years; p < 0.001], had lower median weight [31.0 (20.5-44.5) Kg vs. 40.5 (34.5-49.5) Kg; p < 0.001], had lower median BMI [18.0 (16.5-20.0) kg/m² vs. 19.0 (17.5-20.5) kg/m²; p = 0.007), and slightly lower mean pH at admission [7.1 ± 0.1 vs. 7.2 ± 0.1, p = 0.016]. Free T3 (2.4 (2.0-3.4) vs. 5.1 (4.2-5.5) pmol/L), Free T4 (12.0 (10.7-14.1) vs. 14.4 (14.0-16.2) pmol/L), and TSH 1.8 (1.1-2.9) vs. 2.7 (1.7- 3.2) mIU/L) were significantly lower in ESS patients (p < 0.001 for all). Impaired consciousness occurred exclusively in the ESS group (8.9% vs. 0%, p = 0.034). Median hospital stay was longer among ESS patients, with over a quarter hospitalized for ≥5 days (26.8% vs. 0%; p < 0.001). Kaplan-Meier analysis showed significantly prolonged hospitalization for ESS patients (log-rank p < 0.0001). Patients with ESS [hazard ratio (HR) = 0.31; 95% CI, 0.21-0.45; p < 0.001], pediatric intensive care unit admission [HR = 0.49; 95% CI, 0.29-0.83; p = 0.008], moderate DKA [HR = 0.51; 95% CI, 0.30-0.87; p = 0.014], and severe DKA [HR = 0.28; 95% CI, 0.14-0.57; p < 0.001] were associated with prolonged hospital stay. Conclusions: ESS is significantly associated with prolonged hospital stays in children with DKA. Early identification of ESS may help guide monitoring strategies and discharge planning.