Medscape Nephrology > Berns on Nephrology
COMMENTARY
When Initiating Dialysis, Can eGFR Stand Alone?Jeffrey S. Berns, MD
Disclosures | October 28, 2015
VIDEO:
http://www.medscape.com/viewarticle/852971This is Jeffrey Berns, editor-in-chief of Medscape Nephrology. I recently received an email from a colleague that was sent not only to me, but to a number of other nephrologists around the world, with a copy of the Japanese Society for Dialysis Therapy's clinical guidelines on "hemodialysis initiation for maintenance hemodialysis" (published in Therapeutic Apheresis and Dialysis[1]).
These guidelines generated a fair amount of email discussion over the ensuing several days. A couple of the more salient features in this clinical practice guideline are the following:
Renal function should not be assessed using only serum creatinine levels, but also by using a predictive equation on the basis of serum creatinine values. That has become standard practice.
The time of hemodialysis initiation should be determined by comprehensively assessing the levels of serum creatinine; changes in glomerular filtration rate (GFR) with time; and the physical constitution, age, gender, and nutritional condition of the patient. This is seemingly good advice.
The precise evaluation of renal function at the time of hemodialysis initiation is determined by such measuring methods as inulin clearance test, creatinine clearance (calculated by a 24-hour collected urine specimen), or the sum of clearance values of creatinine and urea divided by 2. The latter is part of my practice very commonly, but estimated GFR (eGFR) doesn't really come into play in these specific recommendations.
Regarding the specifics of timing of hemodialysis initiation—and this is where the controversy really comes in—the guideline states first that the judgment on the time to initiate hemodialysis is allowed when residual renal function shows progressive deterioration and reaction to GFR less than 15 mL/min/1.73 m2 despite sufficient optimal conservative treatment.[1]
The guideline goes on to state that life prognosis after initiation of hemodialysis can be favorable as long as patients can endure, under conservative treatment, until the GFR is less than 8 15 mL/min/1.73 m2. However, from the viewpoint of life prognosis, it is recommended that hemodialysis should be initiated prior to a GFR of 2 15 mL/min/1.73 m2, even when there are no symptoms of renal failure.[1]
This is not a particularly evidence-based guideline, and this point generated a lot of controversy in the email exchange between those who feel that creatinine-based determinations are appropriate for making decisions about initiation of dialysis and those who do not, but who rather feel that other factors should be considered in making dialysis initiation decisions—such as volume status of the patient, potassium, acid/base status, mineral and bone disease issues, symptoms or the lack of symptoms (recognizing that these are very nonspecific), nutritional status (as was mentioned in the Japanese guidelines), changes in some measure or estimate of GFR over time, goals of the patient, and so forth.
There certainly seems to be an increasing inclination to think about non–creatinine-based factors when we are thinking about initiation of dialysis. There is a general consensus that uremia is a vague, ill-defined concept that each of us defines very differently.
One of the comments made during this email exchange was, "I just do not think that the nephrology community should be content with an eGFR creatinine by any equation to assess the level of reduced renal function in very advanced CKD [chronic kidney disease]. It is just too confounded by non-GFR determinants to be a practical value."
Some very important comments were made by Alan Collins, who gave me permission to summarize them. He stated that volume and hypertension are the big areas in the causal path for lactate dehydrogenase, systolic and diastolic function in heart failure, and atherosclerosis. The big mortality in CKD is from cardiovascular disease. The complications of advancing CKD with hyperkalemia limit effective therapies for these, such as angiotensin-converting enzyme inhibitors and other renin-angiotensin system blockers.
He went on to state that the discussion on when to start dialysis must take into account the effectiveness of the nondialysis medical management as well as collaboratively working with patients on their lifestyle choices and the advancing medical realities that unfold with progressive loss of kidney function. He explained why we need to pay more attention to volume status, blood pressure control, and assessment and management of left ventricular hypertrophy, noting that these are more important because they contribute to the morbidity and mortality of our dialysis patients. The creatinine issues—the so-called uremic syndrome—in and of themselves are less important.
This is a very important dialogue. Hopefully it will lead to some refocusing of our attention on a variety of factors that affect our patients as they develop progressive CKD, approaching end-stage renal disease, and drive us away from focusing so much on the eGFR as an isolated laboratory value. The eGFR is just an estimate.
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