The Association of Systemic Inflammation Index with Parathormone Levels in Hemodialysis Patients: A Cross-Sectional Study

Abstract

Aim: Abnormal parathormone (PTH) levels are common in patients undergoing hemodialysis and have been linked to adverse outcomes. This study investigated the association between the systemic inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), and parathyroid hormone (PTH) levels in patients undergoing maintenance hemodialysis (HD). Materials and methods: We performed a cross-sectional analysis of 225 patients undergoing HD at a single center. Demographic data, comorbidities, dialysis vintage, and laboratory values were obtained from medical records. Patients were stratified into three groups based on PTH level according to KDI-GO CKD-Mineral and Bone Disorder (CKD-MBD) guideline targets: PTH1 (< 150 pg/ mL), PTH2 (150-600 pg/mL), and PTH3 (> 600 pg/mL). The SII and NLR were calculated from complete blood counts. We compared the clinical characteristics across the PTH groups and used logistic regression to identify independent predictors of PTH levels outside the target range. Results: Of the 225 patients (mean age 61.3 +/- 17.5 years; 53.3% male), 17.3% were in the PTH1 group, 55.6% in PTH2, and 27.1% in PTH3. Patients in the PTH1 (low PTH) group were older and had a higher prevalence of diabetes mellitus than those in the target PTH group (p < 0.05). Serum calcium and phosphate levels were similar among the groups (p > 0.05). C-reactive protein (CRP) and ferritin levels were significantly higher in both the PTH1 and PTH3 groups compared to the PTH2 group (p < 0.05 for both). Accordingly, the novel inflammatory indices differed by PTH category: the median SII and NLR values were lowest in the PTH2 group and significantly elevated in both the low PTH and high PTH groups (PTH1 and PTH3, p < 0.05). In multivariate logistic regression, higher SII (p = 0.002) and NLR (p = 0.045) were independently associated with PTH levels outside the 150-600 pg/mL target range, even after adjusting for age, diabetes, CRP, ferritin, calcium, and phosphorus. HD duration showed a significant inverse correlation with PTH in the PTH1 group (r = -0.245, p = 0.022) but was not an independent predictor of PTH category overall. Conclusion: Hemodialysis patients with PTH levels below or above the recommended target range demonstrated elevated inflammatory markers (CRP and ferritin) and higher SII/NLR values, indicating a state of increased systemic inflammation. The SII and NLR were independent predictors of out-of-range PTH levels. These easily obtained indices may be useful for assessing inflammation in HD patients with altered mineral metabolism. Further research is warranted to determine whether addressing inflammation can modulate PTH levels or improve outcomes in this population.