Calcium and magnesium flux in automated peritoneal dialysis.

BACKGROUND: Calcium and magnesium balance in continuous ambulatory peritoneal dialysis (CAPD) has been extensively studied with several of the different formulations of fluid available. Calcium and magnesium balance in automated PD (APD) is less well studied and the effect on Ca and Mg flux is unknown. Data on glucose polymer solutions are also lacking. This prospective observational study was undertaken to examine mass transfer of Ca and Mg in APD patients. METHODS: 12 patients on APD were studied for two 24-hour periods using, alternately, 1.75 mmol/L and 1.25 mmol/L Ca (Dianeal PD1 and Dianeal PD4; Baxter Healthcare, Newbury, UK) 1.36% glucose-based dialysis fluid for the 9-hour overnight dialysis, followed by a 15-hour daytime dwell of glucose polymer-based fluid (icodextrin). Serum ionized Ca, serum Mg, and dialysate Ca and Mg concentrations were measured at the beginning and end of each period. Mass transfer was calculated as millimoles per exchange. RESULTS: During rapid overnight exchanges with Dianeal PD1 and PD4, mass transfer of Mg and Ca did not show significant correlations with serum levels when using PD1 fluid; however, mass transfer of Mg, but not Ca, was significantly correlated to serum levels when using PD4 fluid. During the long dwell with icodextrin, dialysate drain volume was the most significant factor determining the flux of both Ca and Mg. CONCLUSION: Mass transfer of Ca and Mg in APD patients using conventional dialysis fluid was not related to drain volume in this study, which differs to studies in CAPD. Flux of Ca and Mg during icodextrin use was found to be dependent on ultrafiltration rate and not dialysate or serum concentration.

Control of serum phosphate by oral lanthanum carbonate in patients undergoing haemodialysis and continuous ambulatory peritoneal dialysis in a short-term, placebo-controlled study.

BACKGROUND: Hyperphosphataemia in dialysis patients is associated with significant morbidity. We assessed the ability of lanthanum carbonate to control phosphate levels in patients undergoing haemodialysis or continuous ambulatory peritoneal dialysis (CAPD) in a short-term, placebo-controlled study. METHODS: This was a double-blind, placebo-controlled, parallel-group study consisting of three phases: a 2 week washout period; a 4 week, open-label, dose-titration phase; and a 4 week, double-blind, placebo-controlled phase. After washout, patients (n = 59) received lanthanum (375 mg/day), titrated up to a maintenance dose (maximum: 2250 mg) that achieved control of serum phosphate levels between 1.3 and 1.8 mmol/l (4.03-5.58 mg/dl). After titration, patients were randomized to receive their maintenance dose of lanthanum (n = 17) or placebo (n = 19) for 4 weeks. Control of serum phosphate was the primary efficacy assessment. Levels of calcium, parathyroid hormone, calcium x phosphate product and lanthanum as well as adverse events were evaluated. RESULTS: By the end of titration, 70% of patients had serum phosphate levels < or =1.8 mmol/l. Lanthanum carbonate continued to control serum phosphate levels in the double-blind phase. At the end of the study, 64.7% of lanthanum carbonate-treated patients were controlled compared with 21.4% in the placebo group. Results in patients receiving CAPD were similar to those seen in the group as a whole. Mean parathyroid hormone levels (P = 0.41) and calcium x phosphate product (P<0.001) were both higher in the placebo than the lanthanum carbonate group. CONCLUSIONS: Lanthanum carbonate is an effective phosphate binder able to control serum phosphate and calcium x phosphate product.

Reducing high phosphate levels in patients with chronic renal failure undergoing dialysis: a 4-week, dose-finding, open-label study with lanthanum carbonate.

BACKGROUND: The majority of patients with end-stage renal disease on dialysis are hyperphosphataemic. Lanthanum carbonate has been shown to be a highly effective phosphate binder in pre-clinical studies. A 4-week, open-label, dose-titration trial was conducted to assess the ability of lanthanum carbonate to control phosphate levels in patients with chronic renal failure. METHODS: This preliminary study was of 6 weeks duration: 2 weeks of washout followed by 4 weeks of dose titration. Patients (n = 59) were titrated on the basis of weekly serum phosphate levels from a daily dose of 375 mg lanthanum carbonate to a maximum dose of 2250 mg. Patients were maintained on the dose that controlled serum phosphate to between 1.30 and 1.80 mmol/l (4.03-5.58 mg/dl). Serum phosphate levels represented the main efficacy assessment. Safety was also evaluated. RESULTS: Most patients were successfully titrated to 1500 and 2250 mg lanthanum/day (mean dose at end of titration: 1278 mg). At completion of the study 70% of patients achieved a serum phosphate of