Prime determinants of serum phosphorus level in hemodialysis patients

The concept that hyperphosphatemia in hemodialysis (HD) patients is a risk factor for various outcomes has now been widely accepted. Many patients on maintenance HD with a high serum phosphorus level are linked to the development of aspects of chronic kidney disease-mineral and bone disorder; they are thus recommended to maintain serum phosphorus level within a normal range [1]. In order to control this, we have options such as dietary restriction and the use of phosphate binders. However, more than half of patients did not reach the target range in the United States, Europe, and Japan [2], and the proportion of patients with hyperphosphatemia may be similar in Korea because the mean serum phosphorus level was reported to be 5.1471.64 mg/dL [3]. Rhee et al [4] reported that the factors associated with phosphate control were different depending on the residual renal function status in Korean patients on maintenance HD. They also emphasized the preservation of residual renal function for the optimal phosphorus control in non-anuric patients. Although I totally agree with the findings of the study, it could not be overlooked that we have only a couple of ways to preserve residual renal function in HD patients, including the use of ultrapure dialysate, biocompatible membranes, avoiding nephrotoxic drugs, decreasing dialysis frequency, and/or avoidance of aggressive water removal [5]. Therefore, I would like to point out that dietary phosphate restriction with appropriate protein intake could be the first strategy for controlling serum phosphorus levels in HD patients. In this regard, as the authors mentioned in the limitations of the study [4], controlling the amount of dietary phosphate may not only be important in designing clinical research, but could also be crucial in the treatment of HD patients with hyperphosphatemia.