Dynamic changes in calcium and phosphate plasma concentrations in the patients on peritoneal dialysis

Abstract

The disturbances of active forms of vitamin D synthesis and disturbances in calcium and posphate metabolism develop early in chronic renal failure, when creatinine clearance is about 30 ml/min. Chronic hemodialysis and peritoneal dialysis only partially correct the biochemical enviroment of patients on chronic renal replacement therapy because of end-stage renal disease. These dialysis modalities can't signifficantly affect the endocrine disturbances of chronic renal failure and they have minimal modulatory effect. The management of disturbed calcium (Ca) and phosphate (P) metabolism and the maintainance of Ca x P product below 4.4 mmol/l thanks to the use of dialysate solutions with the appropriate calcium concentration and the careful dosage of phosphate binders, calcium and active vitamin D metabolits, are extremely important for the prevention of renal osteodystrophy, secondary hyperparathyroidism as well as low-bone turnover disease. The aim of the study was to analyze the plasma levels of calcium, phosphate, albumin, alkaline phosphatase and parathormon (PTH) in 58 patients who were treated with continuous ambulatory peritoneal dialysis (CAPD) from March to August 2003. The use of phosphate binders and the substitution with active vitamin D metabolits were also analyzed. We examined 58 patients, 30 males and 28 female, mean-age 52 years (range, 26-78 years), affected by end-stage renal disease of the different leading cause. The average time on peritoneal dialysis program was 20 months (2-66 months). Most of the patients were treated by CAPD, while only few of them performed authomatic, cyclic or intermitent peritoneal dialysis. Most of the patients used a dialysate with 1.75 mmol/l calcium concentration. The study showed that our patients on chronic CAPD program during several months had normal calcemia, phosphatemia and the level of alkaline phosphatase, and that they had Ca x P product in the recommended range. PTH serum level ranged from 16 to 490 pg/l in our patients. The study showed that a balanced diet and a correct dosage of phosphate binders, as well as a careful substitution with active vitamin D metabolits render a good control of calcium and phosphate serum balance, as well as an effective prevention of renal osteodystrophy development in the patients on chronic peritoneal dialysis treatment.