Long-term effects of reducing the dialysate calcium concentration on bone biomarkers in adult patients on peritoneal dialysis

Abstract

Introduction: Patients on peritoneal dialysis (PD) are usually exposed to a high dialysate calcium concentration (D[Ca]), which is associated with undesirable effects. Low D[Ca] might overstimulate parathyroid hormone (PTH), as shown by previous studies carried out before the incorporation of calcimimetics in clinical practice. We hypothesized that a reduction in D[Ca] is safe and without risk for a rise in serum PTH. Methods in this prospective study, the D[Ca] was reduced from 1.75 mmol/L to 1.25 mmol/L for one year in prevalent patients on PD. Demographic, clinical, and biochemical parameters were evaluated at baseline, 3, 6, and 12 months of follow-up. Results Patients (N = 20) aged 56 ± 16 years, 50% male, 25% diabetic. There was no significant change in calcium, phosphate, alkaline phosphatase, 25(OH)-vitamin D or PTH over time. Medication adjustments included an increase in calcitriol and sevelamer. After 1 year, absolute and percentual change in PTH levels were 36 (-58, 139) pg/ml, and 20% (-28, 45) respectively. The proportion of patients with PTH > 300 pg/ml did not change during the follow-up (p = 0.173). Conclusion Low D[Ca] concentration should be considered to patients on PD as a valuable and safe option. Medication adjustments to detain PTH rising, however, are advised.