Mineral bone disorders (MBD) in patients on peritoneal dialysis

Abstract

Chronic kidney disease-mineral bone disorder (CKD-MBD) is a systemic disorder of mineral and bone metabolism. In patients undergoing peritoneal dialysis (PD), serum levels of calcium (Ca), phosphate (P), and parathyroid hormone (PTH) remain relatively constant, irrespective of the timing of treatment. This is because PD is a continuous blood purification procedure, and in this respect differs greatly from hemodialysis (HD), where the serum levels of these factors change following each dialysis session, and so pre-dialysis values are considered baseline values. Nevertheless, the target values for serum P, Ca, and PTH in PD patients are the same as those in HD patients. In PD patients, however, it is plausible to initiate correction of any of these values once any tendency towards worsening is observed, even if they are still within the upper limit of normal for HD patients. Restriction of dietary P intake, conservation of residual renal function for excretion of P, and prescription of an appropriate P binder are recommended to maintain the blood P level in the appropriate range. The use of a 2.5-mEq/L Ca concentration dialysate reduces the risk of hypercalcemia and allows correction of adynamic bone disease. Meanwhile, secondary hyperparathyroidism may progress in such cases. It is thus recommended that this factor be considered in prescribing this type of dialysate.