Evolution of serum phosphate in long intermittent hemodialysis

Background. Phosphate (P) control is crucial to prevent secondary hyperparathyroidism and extraosseous calcification. Hemodialysis techniques normally used do not remove the amount of P absorbed from an adequate protein intake. Our long hemodialysis (LHD) procedure produces greater P removal in a seven-hour session than in a conventional four-hour session. Our aim was to assess the evolution of predialysis serum P and Ca x P product in patients on intermittent LHD during the first two years on this dialysis schedule. Methods. Eight irregular compliant patients underwent LHD for 12 months; five of them completing 24 months. In the conventional hemodialysis (CHD) period, session time was 12 hours per week, while it was 21 hours per week in LHD. We compared P and Ca x P product throughout both periods; each patient was his or her own control. Results. Mean serum P improved from 7.1 +/- 1.1 mg/dL in CHD to 5.6 +/- 1.1 mg/dL during the second year on LHD (P < 0.05). Mean Ca x P product decreased from 64 +/- 12.7 mg(2)/dL(2) during CHD to 50.9 +/- 10.3 mg(2)/dL(2) at the end of the second year of LHD. Conclusion. By prolonging dialysis time to 21 hours per week, better P serum control and lower Ca x P product were achieved in our patients.