Cross-sectional Study of Calcium Phosphate Product and Intact Parathyroid Hormone Levels in Predialysis and Postdialysis Patients with Stage 5 Chronic Kidney Disease.

Abstract

Chronic kidney disease (CKD) gradually deteriorates the mineral homeostasis, with a disruption of normal serum phosphorus, calcium, and intact parathyroid hormone (iPTH). Hemodialysis is one of the replacement therapies used to treat CKD patients to achieve normal kidney function. The present study aimed to evaluate the impact of dialysis on serum levels of calcium, phosphorus, and iPTH in CKD patients. A cross-sectional observational study was conducted between May 2015 and April 2017 in patients with CKD stage 5. The demographic characteristics including age, sex, body weight, and estimated glomeruli filtration rate were recorded. Serum levels of calcium, phosphorus, and iPTH were measured. A total of 100 patients divided into predialysis (n = 50) and postdialysis group (n = 50) with the mean age 50.34 and 51.88 years were included in this study, respectively. Mean levels of serum calcium and iPTH in the postdialysis patients were significantly lower than predialysis patients (P = 0.0183 and P <0.001). The proportion of patients (74%) with serum phosphorus level >4.5 mg/dL was significantly higher in postdialysis group (0.003). The risk of having high level of iPTH was 3.20 times more among the patients with level of phosphorus between 2.5 and 4.5 mg/dL [odds ratio (OR), 3.20; 95% confidence interval (CI), 1.16-8.80; P = 0.02] and 2.82 times more among patients with level of calcium <8.5 mg/dL (OR, 2.82; 95% CI, 1.13-7.01; P = 0.02). Overall observations suggest a significant reduction in levels of serum calcium and iPTH after dialysis in patients with CKD stage 5.