Abstract
Objective
To examine the effect of a reduced calcium/magnesium dialysis fluid (1.25/0.25 mmol/L, respectively) on calcium and magnesium mass transfer in both 1.36% and 3.86% glucose solutions.
Design
Each patient underwent four test exchanges, two with a standard dialysis fluid containing 1.36% and 3.86% glucose, and two with a reduced calcium/magnesium fluid containing 1.36% and 3.86% glucose. Calcium and magnesium were measured in dialysate and serum at ° and 240 minutes.
Setting
Single renal unit of a university teaching hospital.
Patients
Sixteen patients established on CAPD, and peritonitis-free, for at least 3 months.
Results
A lower dialysate calcium results in negative mass transfer when serum-ionized calcium exceeds dialysate calcium (mean -.0.21±0.15 mmol/exchange), and positive mass transfer when serum-ionized calcium is less than dialysate calcium in 1.36% glucose solutions (mean 0.57±0.18 mmol/exchange). A negative correlation was found between serum-ionized calcium level and calcium mass transfer. With a 3.86% reduced calcium/magnesium solution, calcium mass transfer is always negative (-.0.88±0.18 mmol/exchange) due to ultrafiltration and solute drag.
Fifteen patients were found to be hypermagnesemic at the time of the study. Magnesium mass transfer was neutral with the standard 1.36% glucose fluid (mean -.0.01 mmol/exchange), but negative with the reduced calcium/magnesium 1.36% glucose fluid (mean -.0.58±0.13 mmol/exchange). With the 3.86% glucose solution, both fluids produced negative magnesium mass transfer (mean -.0.32±0.11 and -1.07±0.11 mmol/exchange for standard and reduced calcium/magnesium fluids, respectively).
Conclusions
We conclude that this fluid formulation should reduce hypercalcemia and hypermagnesemia in CAPD patients.
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