Residual renal function and volume status in peritoneal dialysis patients: a conflict of interest?

Fluid status and volume homeostasis are extremely important in patients with CKD stage 5, as cardiovascular disease, including congestive heart failure and hypertension, is one of the leading causes of death in this patient group. Many epidemiologic studies have meanwhile indicated that indeed preservation of volume control is a key component of adequate peritoneal dialysis. On the other hand, residual renal function is also an important and powerful predictor of outcome in peritoneal dialysis (PD) patients. This has led some authors to advocate a state of "slight fluid overload" to preserve residual renal function. This paper seeks to highlight the idea that probably the reason residual renal function is so important, is that it is elementary in the maintenance of a good fluid balance, and that that reasoning should not be inverted. In addition, we will indicate that volume overload in itself might lead to a faster decline of residual renal function. The paper will also point out some important practice points to avoid deterioration of residual renal function in PD patients, such as strict sodium diet and good glycemic control, that are also key to maintaining a good fluid balance.