Download Clinical Benefit of Preserving Residual Renal Function in Dialysis

Clinical Benefit of Preserving Residual
Renal Function in Dialysis Patients: An
Update for Clinicians
Source: Brener ZZ, Kotanko P, Thijssen S, et al.
Clinical Benefit of Preserving Residual Renal
Function in Dialysis Patients:
An Update for Clinicians. Am J Med Sci.
2010;339(5):453–456.
Introduction to Residual Renal Function
• Residual renal function (RRF) plays a vital role in
maintaining fluid balance, phosphorus control and removal
of uremic toxins.
• Decline in RRF is associated with anemia, inflammation and
malnutrition in patients with end-stage renal disease, and
exhibits a dominant predictor of mortality; especially in
patients on peritoneal dialysis (PD).
• Residual renal function in patients on hemodialysis (HD) is
not significant, as RRF declines rapidly in patients on HD.
• The present article provides the data on positive impact of
RRF on the survival and quality of life of patients on
dialysis, and the current strategies to preserve RRF in
patients on PD and HD.
Benefits of Preserved Residual Renal Function
Residual Renal Function and Patient Survival
• In 1995, a study confirmed that there was an independent
relationship between the presence of RRF and survival in patients on
dialysis.
• It was showed that every 1 mL/min increase in glomerular filtration
rate (GFR) was related with a 40% reduced risk of death in the
complete study group and a 50% reduced risk of death in patients on
PD.
• The other study showed that the prognostic power for mortality in
patients on PD was attributed to RRF and not to the dose of PD.
• Therefore, RRF plays a major role in the survival of both patients on
HD and PD and it is suggestive to preserve the RRF.
Residual Renal Function: Volume Control,
Cardiac Hypertrophy and Metabolic Control
• Residual renal function plays a vital role in maintaining the fluid
balance in patients on dialysis. Suboptimal sodium and water
removal in patients on PD leads to greater rates of all-cause
hospitalization and mortality.
• Fluid restriction can be reduced or prevented by RRF.
• There exists an inverse correlation between the left ventricular
hypertrophy and RRF.
• The risk factors for cardiac hypertrophy in patients on dialysis are
associated with RRF.
• The most commonly documented benefit of RRF includes middle
molecule clearance.
• Significant RRF lowers β₂-mocroglobulin levels thereby less chances
of dialysis-associated amyloidosis.
• Preserved RRF is associated with lower blood levels of uric acid,
potassium and aluminum.
Residual Renal Function and Inflammation
• Patients undergoing dialysis are prone to inflammation that
represents a dominant predictor of mortality.
• Loss of RRF is correlated with an increased inflammatory
response as denoted by elevated solute vascular cell
adhesion molecules (vascular cell adhesion molecule 1) and
Creactive protein levels in patients on PD.
• It has also been shown that loss of RRF may be correlated
with increased production of cytokines and impaired renal
elimination of proinflammatory cytokines.
Residual Renal Function and Nutritional Status
• Residual renal function contributes significantly to the
overall nutritional status by enhancing appetite, dietary
protein and total caloric intake.
Measurement of Residual Renal
Function
• The standard means of renal measurement
include GFR measured by isotope clearance.
• The other tests that are used to assess RRF in
CKD include serum creatinine, creatinine
clearance, urea clearance, an average of the
creatinine and urea clearances, and urine
volume.
• The simplest measure of RRF is urine volume.
Preservation of Residual Renal
Function
Impact of Dialysis Modality
• Based on the data from many studies, it was shown
that RRF was preserved more with PD than HD.
• This may be due to better hemodynamic stability with
PD that may minimize ischemic renal insults and the
avoidance of extracorporeal circulation of HD that
encourages systemic inflammation, oxidative stress and
subsequent kidney injury.
• Therefore, patients with RRF should adopt PD as their
initial dialysis modality as strategy to maximize RRF
preservation and thus improve the survival.
Avoidance of Extracellular Fluid
Volume Depletion
• It has been recommended that episodes of volume
depletion in patients to be an independent risk factor for
the loss of RRF.
• A study confirmed that strict volume control in patients on
PD led to decrease in left ventricular hypertrophy and
mean urine volume.
• Despite normal blood pressure, the decrease in RRF may
have been caused by subclinical hypovolemia as a result of
overzealous extracellular fluid volume depletion.
• Moreover, there were no effects of diuretics on RRF and
can be used to provide better control of fluid balance.
Avoidance of Nephrotoxic Insults
• Residual renal function can be preserved by
avoiding the use of radiocontrast agents or
nephrotoxic drugs such as nonsteroidal
antiinflammatory drugs or aminoglycosides.
• Aminoglycoside nephrotoxicity can be avoided
by opting once-daily dosing, avoidance of
concomitant nephrotoxins, monitoring of drug
levels and choice of the least nephrotoxic
aminoglycoside.
Antihypertensive Medications
• Drugs that preserved RRF include angiotensinconverting enzyme inhibitors and calcium
channel blockers.
• This preservation was statistically significant in
patients with PD or HD.
• A study conducted by Li et al. confirmed that
patients on PD treated with ramipril showed
slower rate of RRF loss compared with the
control group.
Summary
• Residual renal function is an advantage to patients on
dialysis.
• Residual renal function is associated with the clearance
of both small- and medium-sized solutes.
• Residual renal function plays a vital role in maintaining
the cardiovascular health, nutritional status and
wellbeing of patients on dialysis.
• Residual renal function exhibits a positive effect on the
survival of patients on PD.
• Residual renal function should be preserved even after
patients are started on dialysis treatment, irrespective
of the modality used.
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