In the last decade or so, both hemodialysis and peritoneal dialysis have made rapid advances in their own technologies. As research has progressed, it has been increasingly observed that the efficacy of the two dialysis modalities varies widely in patients with different types of end-stage renal failure (ESRD). In ESRD patients with high residual urine output, peritoneal dialysis (PD) not only maximizes the efficacy of dialysis, but the quality of patient survival and survival rates are similar to or better than those of hemodialysis (HD) patients. In addition, PD can maintain residual renal function (RRF) status for longer than HD. However, patients with lost or depressed RRF do not have dialysis efficacy comparable to HD. Increasingly, clinical practice has demonstrated that the RRF status of ESRD patients is critical in determining the efficacy of PD and the quality of patient survival. Therefore, it is an important issue for specialists to choose the appropriate indications for PD and to protect the RRF of PD patients. The biggest difference between PD and HD is that the former has minimal hemodynamic fluctuations during dialysis, and the body always maintains a certain volume load, so dialysis itself does not induce or aggravate renal ischemic injury due to ultrafiltration as HD does. This is the key reason why PD is better than HD in protecting RRF. In contrast, HD allows frequent dialyzer changes, which not only stabilizes dialysis, but also maintains the performance of the dialysis membrane for a longer period of time than peritoneal membranes. Thus, it appears that although PD and HD are both important tools for renal replacement therapy, each has its own irreplaceable advantages in terms of treatment rationale. Therefore, the selection of treatment options should be based on the condition of the ESRD patient, especially the RRF status, and should be considered in conjunction with the therapeutic advantages of PD and HD. PD treatment population and advantages For PD, its therapeutic advantages should be targeted at ESRD patients with RRF, especially those with interstitial tubular disease and AKI on top of CRF. In addition to the slow progression of the disease itself, the former is usually associated with varying degrees of circulating blood volume deficiency due to tubular concentration dysfunction. The unique dialysis mode of PD can compensate for this deficiency in terms of the pathophysiological mechanism of the disease and reduce or improve the renal blood flow deficiency and renal ischemia, thus protecting the RRF. In turn, the presence of RRF plays an important role in maintaining the volume balance, regulating blood pressure, and maintaining stable calcium and phosphorus metabolism in ESRD patients. In addition, because the pore size of the glomerular membrane is significantly larger than that of the peritoneum, PD patients have much more nitrogenous products and middle-molecular substances removed by the residual kidney than by the peritoneal dialysis fluid. Therefore, as long as RRF is present, PD can achieve the same or even better dialysis performance as HD. Many studies have also demonstrated that a residual glomerular filtration rate (rGFR) of 1 ml/min corresponds to a volume removal of about 10 L per week from the residual kidney. For every 1 ml/min decrease in rGFR, the clearance of nitrogenous toxins such as urea decreases by about 10 L per week, which indicates that RRF status is the key to successful PD. Therefore, the author believes that all ESRD patients who will undergo PD should be evaluated for RRF status before making a decision. How to Prescribe Dialysis for PD Prescribing dialysis based on RRF status is also the key to improve the efficacy of PD dialysis. Currently, there is no uniform clinical standard for the dosage of dialysis to be used in PD patients, and most of the current dialysis prescriptions depend on the clinical experience of the physician in charge, and the dialysis protocol and dosage are relatively homogeneous. A prominent problem in current PD treatment is that the dialysis dose is not organically related to the patient’s RRF status, body size and metabolic status. In clinical practice, we found that too much dialysis dose does not necessarily increase the dialysis efficacy, but will cause the accelerated decrease of RRF due to the increase of dialysis volume, which will affect the dialysis efficacy; at the same time, it will also increase the loss of protein and other nutrients due to excessive ultrafiltration. If the dialysis dose is not sufficient, it is difficult to excrete the metabolites produced by the body daily. As a result, the same dialysis dose can produce very different results in different patients. Therefore, it is necessary to formulate dialysis prescriptions individually according to the actual status of each patient. Previous studies at our hospital have demonstrated that the amount of nitrogen metabolites removed via the residual kidney is much higher than that of the abdominal dialysis fluid. When rGFR > 4 ml/min, creatinine clearance via the residual kidney accounts for more than 60% of overall creatinine clearance. Therefore, the central role of the residual kidney should be prioritized when developing dialysis protocols. This will not only improve dialysis efficacy, but also help to maintain the stability of RRF. The difference between dialysis dose and RRF and body surface area was found in the analysis of more than 700 patients with different RRF status, and summarized as the following formula: After the individualized dialysis dose was determined with the body surface area and RRF status as important reference data, the majority of patients could maintain good dialysis efficacy, and more prominently, the residual urine volume was maintained for a longer time in these patients. In addition, the volume status of these patients was stable, and cardiovascular system comorbidities were not only less frequent but also later. In conclusion, RRF status is the key to successful PD. Therefore, ESRD patients should be accurately evaluated before deciding to undergo PD. During dialysis, priority should be given to give full play to the role of the residual kidney and enhance protection, minimize or avoid the occurrence of factors that can cause RRF decline, such as long-term repeated use of hypertonic dialysis fluid, nephrotoxic drugs, etc., and strictly control blood pressure and prevent the occurrence of cardiovascular system comorbidities.