Mass Balance

Equation 10 was used to examine mass balance serially during the course of the dialyses reported by Hou et al. [1] with results given in figure 5 . There was a nearly perfect correlation between the sum of change in Ca content of VCa and the sum of MCa and JdCa2+ indicating closure of mass balance.

In 1971 Nolph et al. [2] reported very complete Ca mass balance data during four 24- to 48-hour CAPD treatments with exchanges hourly to treat hypercalcemia due to vitamin D intoxication in a patient with end-stage renal disease. They reported both D Ca2+ and D CaT from measurements of both CCaT and CCa2+ in total dialysate and in plasma during the course of dialyses. Thus Ca re-

CpCa CdiCa Calculated CpCa M = 0

3.50

3.00

2.50

1.50

CpCa CdiCa Calculated CpCa M = 0

3.50

3.00

2.50

Ca

Hou CdiCa 3.5

100 150 Time, min

CpCa CdiCa Calculated CpCa

Hou CdiCa 2.5

CpCa CdiCa Calculated CpCa

100 150 Time, min

Fig. 4. A representative plasma Ca profile in a hypercalcemic patient dialyzed for 3 h with CdiCa = 0. Note that due to mobilization of Ca from the buffer pool, plasma Ca remained in normal range despite a large Ca gradient from blood to dialysate.

C PCa

2.50

2.00

1.50

CdiCa □ Calculated CpCa

2.00

0 0

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