Effect of hemodialysis on the distribution of phosphates in blood.

Phosphate retention is commonly associated with chronic renal failure. Previously we presented a technique to calculate the distribution of phosphate constituents in body fluids. We studied it in pre- and postdialysis serum of 62 patients. After hemodialysis, there was some decrease in the concentration of each constituent, with significant changes in the molar fraction of H2PO4- and CaHPO4. There is a significant negative correlation between the molecular mass of the constituent (X) and the effect of dialysis (Y): urea and H2PO4- 50%; NaHPO4-, HPO4(2-), and creatinine 41-44%; MgHPO4 39%, and CaHPO4 28%. Y = 69.7 - 0.26x, r = -0.833, p less than 0.001. This limited removal of CaHPO4 may contribute to the vascular calcification and peripheral ischemic necrosis of chronic uremic patients.