Adequacy of dialysis in children: does small solute clearance really matter?

Measurement of dialysis adequacy relies on an assessment of small molecule clearance during the dialysis procedure. However, recent adult studies (HEMO and ADEMEX) that pushed clearance to maximally achievable levels within practical constraints of thrice-weekly hemodialysis or four times daily continuous ambulatory peritoneal dialysis failed to demonstrate improvements in patient outcome above current guidelines. The relatively low incidence of pediatric compared with adult end-stage renal disease limits large-scale study of pediatric dialysis. Several single-center pediatric studies demonstrate a lack of association between small solute clearance alone and patient growth. The aim of the current article is to review the relevant pediatric and adult studies of small solute clearance and put them in the context of optimal dialysis provision. While small solute clearances do indeed matter, clearance is not all that matters. Our quest to provide optimal dialysis requires that we also focus our attention on patient nutritional status, increased dialysis delivery (daily/nocturnal hemodialysis), and adjunctive dialysis modalities (hemofiltration and renal tubular replacement therapy).