Phosphate Nutritional Intake Control between Patient Undergoing Conventional Thrice Weekly and Infrequent Hemodialysis

Introduction. It is largely agreed that preservation of residual kidney function (RKF) has a directly proportional effect on general and, in particular, cardiovascular mortality. Unlike the oligoanuric patient undergoing thrice weekly hemodialysis (TDH) evaluation of patients on infrequent (once-weekly or twice-weekly) hemodialysis (ID) shows the importance of phosphaturia and residual diuresis are frequently underestimated. Indeed, the native kidney preserves the ability to eliminate not only toxic molecules but also achieve a significant output of phosphate despite a severe decrease in RKF. But without a tailored hypoproteic-hypophosphoric nutritional approach it was not possible to recruit patients for whatever programs of infrequent hemodialysis. Aim. The aim of our study was to assess phosphate balance in patients on ID compared to those on conventional THD with no residual kidney function. Methods. In each group the proteic/phosphoric intake was estimated. Thirty-seven patients were recruited: 12 on THD, 15 on twice-weekly dialysis and 10 on once-weekly dialysis with a combined diet dialysis program (CDDP). A total of 36 urine samples were collected from 36 THD patients and grouped according to dialysis method employed: high efficiency dialysis (HDH), post-dilution on-line hemodiafiltration (postHDF), or pre-dilution hemodiafiltration (preHDF). Fifty-seven urine samples were obtained from patients on TWD, and 109 from CDDP. Results. Compared to THD patients, patients on ID were characterized by a negative or neutral balance between input/output of phosphates. Weekly balance: THD: +4.45; TWD: - 0.73; CDDP: - 0.38. Conclusions. A tailored ID, together with a low-protein – low-phosphorus diet may delay the need for THD and prolong patients’ quality of life and cardiovascular survival, being proportionally linked to a lack of accumulation of dietary phosphate.