Determinants of fatal outcome in septic shock patients with euthyroid sick syndrome

Septic shock is a leading cause of mortality in intensive care, and euthyroid sick syndrome (ESS) may influence outcomes. Identifying predictors of fatal outcome in this population is crucial for guiding management.

To identify clinical and laboratory predictors of 28-day mortality in patients with septic shock and ESS, and to evaluate the prognostic value of markers such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), prognostic index (PI), and modified Glasgow prognostic score (mGPS), the vasoactive drug-dependent index (VDI), and shock index (SI).

In this prospective observational study, 95 patients with septic shock and ESS admitted between May 2024 and August 2025 were analyzed. Demographic, clinical, and laboratory data were collected at admission and on days 1, 3, and 7. Prognostic markers - NLR, PLR, PI, and mGPS, VDI, and SI were analyzed. Associations with 28-day mortality were evaluated using standard statistical tests.

Of the 95 patients (mean age 61 ± 14.6 years; female/male ratio 52/43), 53 (52%) died. Duration of mechanical ventilation (P = 0.013) and intensive care unit (ICU) length of stay (P = 0.005) were significantly associated with mortality. Acute Physiology and Chronic Health Evaluation II (P = 0.014) and Simplified Acute Physiology Score II (P = 0.001) scores correlated positively with fatal outcome. Predictive laboratory parameters included base excess and free thyroxine (FT4) at admission (P = 0.013, P < 0.001); free triiodothyronine and FT4 on day 1 (P = 0.007, P < 0.001); red blood cells (RBC) and lymphocytes on day 2 (P = 0.027, P = 0.049); and white blood cells, pO₂, thyroid-stimulating hormone, and FT4 on day 3 (all P < 0.05). Variables positively correlated with mortality included neutrophils, lactate, C-reactive protein, and albumin, while pH, pO₂, bicarbonate, RBC, platelets, and thyroid hormones were negatively correlated. SI on day 3 (P = 0.027) and mGPS on day 1 (P = 0.030) were significant prognostic indices.

The 28-day mortality among patients with septic shock and ESS was 52%. Duration of mechanical ventilation, ICU stay, severity scores, laboratory parameters, and indices such as SI and mGPS were significantly associated with outcome. The presence of ESS may contribute to adverse prognosis, and combined evaluation of clinical and laboratory factors can improve risk stratification in this high-risk population.