Incidence of Hypercalcemia in Dialysis Patients: HD vs. CAPD

Kim, Jeong Ho; Yi, Hyeon A; Jung, Mi Kyung; Lee, Eun Young; Cha, Mi Kyung; Song, Kyoung Il; Park, Min Sun; Han, Dong Cheol; Hwang, Seung Duk; Lee, Hi Bahl

Abstract

Oral phosphate binders and high calcium dialysate have been used as standard therapies for dialysis patients to prevent renal osteodystrophy. Calcium containing phosphate binders are used to prevent intestinal absorption of dietary phosphate and to avoid aluminum loading by using aluminum containing phosphate binders. The use of calcium products resulted in hypercalcemia in a substantial portion of dialysis population. Calcium carbonate as a phophate binder is widely used in Korea. However, the incidence of hypercalcemia in Korean dialysis patients has not been reported to date. In this study we evaluated the incidence of hypercalcemia in dialysis patients. Patients with associated diseases that may influence serum calcium level were excluded from the study. A total of 180dialysis patients (116 HD patients and 64 CAPD patients) maintained at Soon Chun Hyang University Hospital were included. Three consecutive 2 monthly measurements of serum calcium, phosphate, albumin, alkaline phosphatase, bicarbonate in HD and two consecutive measurements in 3 month interval in CAPD patients were retrospectively evaluated. Ionized calcium and intact parathyroid hormone (N-terminal) were measured every 6 months. Serum total calcium level was corrected by serum albumin level. Three HD patients(2.5%) were hypercalcemic pre-HD while 50(43.1%) hypercalcemic postdialysis. 5 CAPD patients(7.8%) were hypercalcemic. Pre-HD calcium level did not differ from the value in CAPD patients. An average value of pre-and post-HD calcium, and serum albumin levels were significantly higher in HD patients than those values in CAPD patients(p<0.01). Ionized calcium (p<0.01) and serum PTH(p<0.05) levels were significantly higher, while serum bicarbonate level (p<0.01) was significantly lower in HD patients than in CAPD patients. The amount of calcium carbonate used were 2.2g in HD and 2.8g in CAPD. In conclusion, the incidence of hypercalcemia is low in pre-HD (2.5%) and in CAPD patients(7.8%). However, the high incidence of post-HD hypercalcemia observed in this study advocates a future study to evaluate the effect of low calcium dialyste on calcium-phosphate metabolism.