Preservation of residual renal function with HDF.

UNLABELLED: Previous studies have shown that the presence of the residual renal function (RRF) is associated with a lower mortality risk in hemodialysis (HD) patients. A factor promoting a decrease in the RRF has been reported to be dehydration. Therefore, we performed HD or online hemodiafiltration (HDF) without water removal, in which intravascular dehydration due to water removal during dialysis are avoided. We also examined the RRF-maintaining effects of online HDF. Water removal-free dialysis study: The subjects were 44 HD patients within 3 months after the introduction of dialysis. They were divided into two groups: a group undergoing water removal-free dialysis at least for more than 3 months (group A) and a group undergoing dialysis with water removal (group B). Group A consisted of 28 patients including 5 in whom online HDF was initially introduced. Group B consisted of 16 patients on HD with water removal. In each group, the 24-hour urine volume was examined. The follow-up period was 36 months. In group A, the daily urine volume after 6 months or more was significantly larger. The mean water removal-free dialysis period was 18.1 ± 16.2 months. Study of the effects of online HDF on the RRF: The subjects were 49 patients undergoing maintenance dialysis. The 24-hour urine volume was measured. We compared an online HDF group (n = 37) with a HD group (n = 12). We examined the relationship between the duration of dialysis and urine volume. In the HDF group the r value was 0.333 (p = 0.044) and in the HD group it was 0.834 (p = 0.007). There was a significant difference in the correlation coefficient between the two groups (p = 0.024), suggesting that HDF is more useful than HD for maintaining the urine volume for a prolonged period.
CONCLUSION: The online HDF and dialysis without water removal are useful to preserve the RRF.