Adequacy of dialysis in children and adolescents: more than just Kt/V.

The concept of dialysis adequacy has evolved over time. Initially, the focus of dialysis adequacy was on the clearance of small molecules, namely urea. However, limitations of urea-based adequacy assessment and the importance of other elements have become increasingly recognized. There is growing evidence that removal of middle molecules is associated with improved clinical outcomes. Besides clearance of solutes, several clinical markers serve as measures of adequate dialysis. Phosphorus control can have many clinical benefits, but although phosphorus is a small molecule, the kinetics of phosphorus removal by dialysis are different than that of urea. Cardiovascular comorbidities and outcomes are heavily influenced by appropriate volume control, avoiding both excess fluid overload and volume depletion. Growth is an important outcome that does not correlate with urea clearance but may be better achieved using an intensified dialysis schedule and/or a modality that promotes removal of middle molecules. Rather than focusing solely on factors identified by the medical community, adequate dialysis should also address factors identified by patients and their families, including intradialytic and interdialytic symptoms, life participation, and quality of life. There is a bidirectional relationship between dialysis adequacy and both residual kidney function and dialysis access. Rather than applying a standard fixed prescription to all patients, there should be greater emphasis on personalizing the dialysis prescription using shared decision-making with the patient and family.