Assessment of dialysis adequacy: beyond urea kinetic measurements

Abstract

Adequacy of dialysis is a term that has been used for many years based on measurement of small solute clearance using urea and creatinine. This has been shown in some but not all studies in adults to correlate with survival. However, small solute clearance is just one minor part of the effectiveness of dialysis and in fact ‘optimum’ dialysis, rather than ‘adequate’ dialysis is what most paediatric nephrologists would want for their patients. Additional ways to assess the success of dialysis in children would include dialysis access complications and longevity, preservation of residual kidney function, body composition, biochemical and haematological control, nutrition and growth, discomfort during the dialysis process and psychosocial adjustment including hospitalisation and school attendance. These criteria need to be balanced against a dialysis programme that has the least possible adverse effects on quality of life.

Protein energy wasting; what is it and what can we do to prevent it?

“…Inadequate clearance due to poorly functioning access during dialysis, or infectious or thrombotic complications of it, is a source of chronic inflammation. The better form of access is an AV fistula (AVF) in preference to a central venous line as AVF is associated with less infection, longer access survival and less hospitalisation [22]. Haemodiafiltration (HDF) seems to offer some benefit in reducing inflammation and oxidative stress and allows improved removal of middle molecules by convection.…”

Nocturnal home hemodialysis in children: Advantages, implementation, and barriers

“…In the current era, provision of optimum dialysis is not limited to improved urea and creatinine clearance but improved middle molecule clearance, adequate growth and development, nutritional status, biochemical and hematological control, conservation of residual kidney function, and decreasing discomfort during the dialysis procedure are other factors that need consideration . Middle‐sized molecules like β2 microglobulin and protein‐bound molecules, which have a slower removal, contribute to complications like systemic amyloidosis in patients on chronic dialysis.…”

“…The residual kidney function and renal tubular secretion of proteins not only reduce the plasma levels of protein‐bound solutes and middle molecules cleared poorly by hemodialysis but also help in phosphate and potassium clearance and reduce the requirement for erythropoietin . Avoidance of nephrotoxic medications and reduction in the intradialytic hypotensive episodes can help in the preservation of residual kidney function . In addition, albumin losses are often encountered in intensive HD regimens due to highly permeable membranes .…”

“…The nephrologist's definition of optimum dialysis is one that is adequate, has a well‐functioning vascular access, good native urine output, preserves the residual kidney function, has minimal intradialytic weight gain, and is least associated with the long‐term morbidities of chronic dialysis. Hence, a dialysis modality that provides adequate dialysis but also allows the child to have a good quality of life should be targeted …”

“…Hence, a dialysis modality that provides adequate dialysis but also allows the child to have a good quality of life should be targeted. 2 Traditionally, adequacy of dialysis was assessed using small molecule clearance like urea and creatinine using equations like Kt/V urea (K-dialyzer clearance of urea, T-dialysis time, and V-volume of distribution of urea). However, lack of an optimum Kt/V urea in case of children is a limitation for its use.…”