Abstract
The removal rate of inorganic phosphate in 75 chronic hemodialysis patients was calculated to be 52.3±9.98% (mean±SD, n=75) by sampling blood of the pre- and postdialytic period. The removal rate showed no positive correlation with total dialyzed blood volume, which was estimated by blood flow rate (ml/min) × surface area of dialyzer (m2). There were no significant differences in phosphorus removal rate between various membranes such as Cuprophan®, EVAL, PAN and cellulose acetate. However, the higher predialytic serum inorganic phosphate showed a significantly higher removal rate. Mass removal of phosphorus was measured in six patients who were dialyzed for 5 hours with Rhodial 75 (recirculating dialysate-supplying system) and an H 12 2400 dialyzer (PAN, 1.0m2). The value ranged widely from 540 to 1500mg/treatment and the mass removal was larger in cases with a higher predialytic serum inorganic phosphate level.
The dietary intake of phosphorus was calculated in 50 patients, and was revealed to be 982±192mg/day (mean±SD, n=50). Restriction of dietary phosphate intake was, thus, not fully satisfactory in our center and the proportion of patients with a predialytic serum P level of more than ranged 5.5mg/dl was from 30 to 65% monthly.
Inorganic phosphate output of anuric chronic hemodialysis patients was estimated to be about 830mg/day (renal=0, HD=1, 000mg, fecal=400mg/day).
Consequently, the principle means of preventing phosphate retention and hyperphosphatemia include appropriate restriction of dietary phosphate intake (less than 830mg/day) and use of phosphate binding agents.
Mass removal of inorganic phosphate should be measured precisely with each therapeutic modality for each membrane, since inorganic phosphate removal by blood purification methods is the most important factor to handle in chronic hemodialysis patients.
