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[Dr. Shapiro] This is Dr. Samantha Shapiro, executive editor of Harrison's Principles of Internal Medicine. Harrison's Podclass is brought to you by McGraw Hill's AccessMedicine, the online medical resource that delivers the latest trusted content from the best minds in medicine. And now onto the episode.
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[Dr. Handy] Hi everyone, welcome back to Harrison's Podclass. We're your co-hosts. I'm Dr. Cathy Handy.
[Dr. Wiener] And I'm Dr. Charlie Wiener and we're joining you from the Johns Hopkins School of Medicine.
[Dr. Handy] Welcome to episode 110, a 67-year-old patient with chronic kidney disease.
[Dr. Wiener] Okay. Today, Cathy, we have a 67-year-old woman with known stage four chronic kidney disease that was due to a preexisting focal segmental glomerulosclerosis. And the question is going to ask, which of the following is an indication for the initiation of hemodialysis?
[Dr. Handy] Oh, we've actually never talked about this before on one of our episodes.
[Dr. Wiener] Yeah, but before we get to the question, let's quickly review the stages of chronic kidney disease. I mentioned this woman is stage four.
[Dr. Handy] The important point is that staging of chronic kidney disease is based on an estimation of the glomerular filtration rate, not the serum creatinine. To estimate the GFR, or the glomerular filtration rate, we use equations but remember, this assumes the patient is in a steady state, not in active acute kidney injury. Many institutions have also recently updated their equations removing race from the calculation. So clinicians should be aware of what equations their lab is using and especially if there was a recent change in estimating the GFR. Also, the presence or magnitude of albuminuria can modify the staging.
[Dr. Wiener] Okay. Well, how does the estimated glomerular filtration rate, or GFR, how does that translate to staging?
[Dr. Handy] The staging goes from one to five with stage one being a normal GFR and stage five being so-called end-stage renal disease with an estimated GFR less than 15 milliliters per minute per 1.73 meters squared. And those patients are typically receiving renal replacement therapy. Stages two to three are mild to moderate impairment, and that would be an estimate of a GFR of 30 to 90. Our patient is stage four, so that would be considered severely decreased with a GFR between 15 and 30.
[Dr. Wiener] Great. So the question's asking in this patient, which of the following is an indication for the initiation of maintenance hemodialysis? And the options are A. acidosis controlled with daily bicarbonate administration; B. a bleeding diathesis; C. a BUN greater than 110 without symptoms; D. a creatinine greater than 5 without symptoms; or E. hyperkalemia controlled with sodium polystyrene.
[Dr. Handy] Well, the answer is B. The presence of a bleeding diathesis in a patient with stage four CKD would be an indication for starting maintenance hemodialysis.
[Dr. Wiener] But let's just step back and tell me what are the usual indications for instituting hemodialysis.
[Dr. Handy] So the commonly accepted criteria include the presence of uremic symptoms, the presence of hyperkalemia that's unresponsive to conservative management, persistent extracellular volume expansion, despite diuretics, acidosis refractory to medical therapy, a bleeding diathesis or a creatinine clearance or estimated GFR rate below 10 to 15.
[Dr. Wiener] Okay. So you mentioned again bleeding diathesis but those BUNs and creatinines were pretty notable. What about them?
[Dr. Handy] Yeah, single blood urea nitrogen or BUN or creatinine values alone are inadequate to initiate maintenance dialysis. Now obviously, there's a relationship between the numbers and the indications for maintenance dialysis therapy, but they're not necessarily absolute indications to initiate.
[Dr. Wiener] Okay. Since we've never discussed dialysis before, let's quickly review how we should approach the outpatient with stage four chronic kidney disease, such as this woman.
[Dr. Handy] Well, first I want to remind folks that all patients with stage four CKD should be aware of and followed for the complications that are associated with a failing kidney. So things like hypertension, anemia, metabolic acidosis, and secondary hyperparathyroidism should all be addressed proactively.
[Dr. Wiener] What about referral to a nephrologist?
[Dr. Handy] Yeah, it's important that the primary care provider refers a patient like this who is likely to require chronic maintenance renal replacement therapy to a nephrologist. And this allows time for discussions and advanced planning about the type of dialysis and therefore, the establishment of stable dialysis access. Also, recent data have suggested that a sizable fraction of end-stage kidney disease cases result following episodes of acute kidney injury, particularly among patients with underlying CKD. So if a patient has been hospitalized recently, they're likely to require closer monitoring.
[Dr. Wiener] And what about the timing of initiation of dialysis?
[Dr. Handy] There's no benefit to initiating dialysis preemptively just for a low GFR compared to initiating dialysis for symptoms of uremia or the indications that I mentioned earlier.
[Dr. Wiener] Okay. Well, let's also briefly talk about the modes of chronic hemodialysis or maintenance hemodialysis. And you mentioned dialysis access, let's talk a little bit about that too.
[Dr. Handy] The basic options are hemodialysis or peritoneal dialysis. There have been no large-scale clinical trials comparing outcomes among patients randomized to either hemodialysis or peritoneal dialysis. Now, while mortality rates for patients on dialysis are much higher than the general population, there does not seem to be a difference in mortality based on mode of dialysis. The decision of which modality to select is often based on personal preferences and quality of life considerations. In the US, over 85% of dialysis patients utilize in-center hemodialysis.
[Dr. Wiener] Great. And so I assume that requires vascular access, whereas peritoneal dialysis would require placement of a peritoneal catheter?
[Dr. Handy] Exactly right.
[Dr. Wiener] Okay. So the teaching points for this case are that patients with chronic kidney disease are staged based on their estimated GFR and the presence of microalbuminuria, which we did not talk about much, but the tables are listed in common textbooks. Patients with stage four kidney disease should likely be referred to a nephrologist for dialysis planning. The indications for institution of dialysis are mostly clinical, such as a bleeding diathesis or failures of medical therapy related to volume, acidosis, or potassium excretion. Hemodialysis or peritoneal dialysis based on availability and patient preferences are the usual modes of dialysis.
[Dr. Handy] And you can read more about this in the chapter on dialysis and the treatment of kidney failure.
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[Dr. Shapiro] Thanks for listening to Harrison's Podclass. You can listen to this episode and more on AccessMedicine.com which includes the complete Harrison's Principles of Internal Medicine text, Harrison's Review Questions, which complement and expand upon the questions in this episode, and much more. AccessMedicine.com may already be available to you via your academic institution. Check it out!
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