Predictors of Residual Kidney Function in Hemodialysis Patients

Residual renal function should be preserved even in hemodialysis patients
Residual renal function can be predicted using trace protein (βTP) and β2-microglobulin (β2M)
βTP and β2M concentrations were found to reasonably predict concentrations of residual urea clearance of 2 ml/min/1.73 m² or more.

Trace proteins can be used to predict residual kidney function as it is of great significance among patients undergoing hemodialysis.

Significance of Residual Kidney Function

Hemodialysis is not qualitatively equivalent to residual renal function and, therefore, the residual renal function should be preserved.

Dialysis - Hemodialysis, Peritoneal Dialysis and Role of Diet and Drugs
Dialysis is an artificial process for removing excess water and waste from the blood. Hemodialysis and peritoneal dialysis are the types of dialysis.

‘Trace proteins βTP and β2M may be better predictors of glomerular filtration rate (GFU) in hemodialysis patients.’

Tweet it Now

Residual renal function aids in

Clearance of small solutes
Helps in the maintaining the fluid balance
Maintaining phosphorous control
Improving anemia
Elimination of uremic toxins of middle molecular weight

Residual renal function in dialysis patients has an inverse relationship with

Cardiac hypertrophy
Valvular calcification

A slump in residual renal function in dialysis patients results in;

Anemia
Malnutrition
Inflammation

The complete loss of residual renal function among patients undergoing hemodialysis is a strong predictor of mortality.

Residual renal function is very significant among patients on dialysis. The Kidney Diseases Outcomes Quality Initiative (KDOQI) guidelines indicate that hemodialysis can be reduced among patients with 2 ml/min/1.73 m² or more of Residual Urea Clearance (KRU). This requires routine monitoring of the residual renal function.

Drawbacks in the Current Method of Measuring Residual Renal Function

The current methods for assessing residual renal function have the following limitations

A. The method involves collecting interdialytic urine which is relatively complicated

Quiz on Dialysis
Dialysis is a common procedure performed in patients with kidney failure, especially those who are awaiting kidney transplantation. Test your knowledge on dialysis by taking this quiz.

B. Urea and creatinine clearance are measured which are also dependent on the muscle mass, gender and diet of the individual.

This makes prediction of residual renal function difficult. The latest study by Wong et al. and colleagues in the paper titled “Predicting residual kidney function in hemodialysis patients using serum β-trace protein and β2-microglobulin” in the journal Kidney International (May 2016) identifies a better marker.

Dialysis Efficiency (Kt/V) Calculator
Dialysis Efficiency Calculator or Kt/V calculator is an interactive tool that indicates how well dialysis is working for you and checks if enough water and waste products are cleared from your blood.

Properties of βTP:

βTP is also called lipocali- type prostaglandin D synthase. This 23 kDa glycoprotein is excreted exclusively by the kidneys but is present in the brain, heart, retina, testis and kidney. The residual urine output has been correlated with βTP concentrations but the study by Wang et al. is the first to explore its relevance in identifying residual kidney function among hemodialysis patients.

Properties of β2M:

Kidney Function Tests are a better Indicator of Cardiovascular Disease Risk
Glomerular filtration rate and albuminuria improved prediction of cardiovascular diseases, particularly heart failure and death from heart attack and stroke.

β2M is 11.8 kDa and is found to accumulate in patients with kidney failure. This trace protein is a significant determinant of residual kidney function in a hemodialysis patient.

Equations to Predict GFR and KRU Using βTP and β2M

231 patients on hemodialysis were included in the study. 191 patients were assessed to model the equation for glomerular filtration rate (GFR) and residual urea clearance (KRU) while the rest 40 patients were used to validate the earlier findings.

The trace proteins were used to determine the linear regression model for GFR and KRU using only

βTP
β2M
Both β2M and βTP

The equations that used both β2M and βTP showed greater accuracy in estimating GFR and KRU than when only a single component was used.

Estimated GFR and KRU

Source: Jonathan Wong, Sivakumar Sridharan Jocelyn Berdeprado, Enric Vilar1, Adie Viljoen, David Wellsted, Ken Farrington; “Predicting residual kidney function in hemodialysis patients using serum β-trace protein and β2-microglobulin”; Kidney International, May 2016.

Validation of the Equations:

The values of GFR and KRU obtained using the equation were validated by assessed using the validation study participants. It was found that estimation and validation values from the respective study subjects correlated significantly.

The equations were used to study the value of KRU and to follow KDOQI guidelines in altering hemodialysis. The value of KRU estimated using the equations in the study correlated with measured KRU values.

Though the study sample used for validation was small, the results of the study show promise for a better method of estimation of KRU. This would limit the need for interdialytic urine collection and provide a better monitoring system.

References:

Jonathan Wong, Sivakumar Sridharan Jocelyn Berdeprado, Enric Vilar1, Adie Viljoen, David Wellsted, Ken Farrington; “Predicting residual kidney function in hemodialysis patients using serum β-trace protein and β2-microglobulin”; Kidney International, May 2016
A.Y.-M. Wang, K.-N. Lai, “The importance of residual renal function in dialysis patients”, Kidney International, May 2006.
Measurement of residual renal function in HD
http://ndt.oxfordjournals.org/content/17/suppl_7/11.abstract

Source-Medindia