Calcium, magnesium mass transfer and lactate balance study in CAPD patients with reduced calcium/magnesium and high lactate dialysis fluid.

We studied calcium (Ca), magnesium (Mg) mass transfer (MT) in 10 and lactate balance in 5 CAPD patients using standard dialysis solution [(ST) (Ca 1.75 mmol/l; Mg 0.75 mmol/l; lactate 35 mmol/l)] and with reduced Ca/Mg, high lactate solution [(LC) (1.25 mmol/l; 0.25 mmol/l; 40 mmol/l respectively)]. Exchanges were performed with 1.36% and 3.86% glucose solutions. MT was calculated as mmol/exchange. Ca MT was +0.96 and +0.39 with ST 1.36% and 3.86% glucose respectively. Serum ionised Ca (iCa++) levels were less than fluid Ca during these exchanges. With LC 1.36% glucose it was -0.66 when ICa++ was more than dialysate Ca, but +0.66 when iCa++ was less than dialysate Ca. Ca MT was negative with LC 3.86% glucose irrespective of iCa++ levels. All patients were hypermagnesaemic (mean 1.24 mmol/l. Mg MT was +0.21 and -0.04 with ST 1.36% and 3.86% glucose respectively and -0.62 and -1.13 with LC 1.36% and 3.86% glucose respectively. The difference between mean lactate gain and bicarbonate loss was less (-0.4) during exchange with LC 1.36% glucose. Mean plasma TCo2 and plasma pH did not differ between ST and LC solutions. We conclude that reduced Ca/Mg, high lactate solutions should reduce hypercalcaemia/magnesaemia and maintain a better acid base balance in CAPD patients who may require Ca/Mg containing phosphate binders.