Diagnostic Performance of Plasma Levels of <scp>sST2</scp> (Soluble Suppression of Tumorigenicity 2) in the Evaluation of Hypervolemia in Hemodialysis Patients: A Comparative Analysis With Traditional and Alternative Biomarkers

BACKGROUND: Persistent hypervolemia in patients undergoing maintenance hemodialysis is a major modifiable determinant of cardiovascular morbidity and mortality. Accurate estimation of dry weight and identification of hypervolemia remain challenging due to limitations of current assessment methods. OBJECTIVE: To evaluate the diagnostic performance of plasma levels of sST2 (soluble suppression of tumorigenicity 2), a biomarker reflecting myocardial stress and fibrosis, in detecting clinician-defined hypervolemia in hemodialysis patients, and to compare it with plasma levels of B-type natriuretic peptide (BNP) and the plasma fibrinogen to serum albumin ratio (FAR), indicators of hemodynamic and inflammatory stress. METHODS: This single-center, prospective cross-sectional study included 80 maintenance hemodialysis patients. Hypervolemia was defined by a nephrologist based on structured clinical assessment, supported by findings from bioelectrical impedance analysis, echocardiography, and chest radiography. Predialysis blood samples were analyzed for BNP, sST2, fibrinogen, and albumin. Diagnostic accuracy was assessed using receiver operating characteristic (ROC) analysis. RESULTS: Of the 80 hemodialysis patients included in the study, 45 were classified as euvolemic and 35 as hypervolemic. Compared with the euvolemic group, hypervolemic patients exhibited significantly higher pre- and post-dialysis blood pressure, greater interdialytic weight gain, higher ultrafiltration volumes, and increased left ventricular mass index and left atrial diameter (all p < 0.05). FAR levels were significantly elevated in hypervolemic patients (110.9 ± 35.0 vs. 89.1 ± 23.9; p = 0.002). In ROC analysis, FAR demonstrated the strongest discriminative ability for identifying hypervolemia (area under the curve [AUC]: 0.714), outperforming BNP (AUC: 0.645). A FAR cut-off value of ≥ 106 achieved 60% sensitivity and 84.4% specificity. In contrast, sST2 did not display diagnostic discriminative performance (AUC: 0.490). CONCLUSION: In hemodialysis patients, the FAR demonstrated moderate diagnostic accuracy in identifying hypervolemia and showed better discriminative performance than BNP, whereas sST2 did not provide diagnostic value. These findings indicate that no single biomarker is sufficient for volume assessment and support the use of a multimodal approach. Within this context, FAR may represent an emerging biomarker for integration into multimodal evaluation.