Prognosis comparison in chronic kidney disease stages 4–5 patients with low parathyroid hormone level due to different causes

Background Existing studies have focused on secondary hyperparathyroidism with elevated PTH in CKD, but survival outcomes of CKD patients with low PTH remain underexplored. This study examines prognostic implications of PTH reduction from different etiologies. Methods This multicenter retrospective cohort study included CKD stages 4–5 patients with PTH < 150 pg/mL from the China Renal Data System, categorized into parathyroidectomy (PTX), Drug, and Unknown Causes (UC) groups based on low PTH etiology. Mortality was analyzed using Kaplan-Meier curves and Cox regression. Covariates were selected by univariate or LASSO regression. Inverse probability weighting was applied in sensitivity analyses to reduce confounding. Results A total of 17 175 patients were included: 423 in the PTX group, 10 519 in the Drug group, and 6 233 in the UC group. PTX group had the highest survival rate (79.44%) and lowest cardiovascular mortality (1.61%), followed by Drug group (69.21% and 4.60%) and UC group (50.76% and 9.83%) (all P < 0.01). Both Drug group and UC group were consistently associated with significantly higher mortality risk compared with the PTX group (both P < 0.05). After applying IPW to balance key covariates, PTX group remained associated with the lowest mortality risk (both P < 0.05). However, in some sensitivity analyses, no significant difference was observed between PTX group and Drug group. Conclusions Pharmacological therapy and PTX were associated with more favorable survival profiles than low PTH of unknown causes in patients with advanced CKD, though residual confounding due to baseline differences between groups cannot be fully excluded.