Transcript
A (0:00)
Welcome back to Run the List, a medical education podcast in internal medicine. As a quick disclaimer, this podcast is made for educational and informational purposes only and should not be understood as medical advice under any circumstances. Before we get to the show, a quick word on the sponsors for today's episode.
B (0:15)
Open Evidence is the premier AI powered medical information platform for physicians and medical students. It's like ChatGPT for anyone who practices clinical medicine. Whether you have a clinical question, a question that comes up during your literature review, if you have a question that comes up when you're trying to synthesize a topic you're going to teach, you can just go to openevidence.com enter your question and it'll synthesize the answer for you while also linking to those actual articles. It's an outstanding resource. Hey everyone, welcome back to Run the List. This is your host, Walker Red, and I'm thrilled today to have Ryan Bonner as our guest on the podcast. I first had the chance to work with Ryan when we were both residents at the West Roxbury VA up in Boston and he is now an assistant professor of medicine in the Division of Nephrology and Hypertension here at the University of North Carolina. He's known around here as an innovative and outstanding educator. So I'm thrilled to have him joining us today for what's going to be a two part episode on chronic kidney disease. All right, so without any further ado, we're going to go ahead and run the list. We're going to start today with a very brief clinical vignette. Let's just imagine you're in primary care clinic and you have a new patient who's there to establish care. He is a 52 year old man named Mr. M and he's new to the area. On your review of the records prior to clinic, there really are only limited available records to look through. There is mention of chronic kidney disease and a couple other comorbidities in the chart. So Ryan, what's your general advice on how to accurately think about how we measure kidney function?
C (1:55)
Yeah, so thanks for having me, Walker. It's great to be here. You know, we assess kidney function or estimated glomerular filtration rate oftentimes based on serum creatinine. So serum creatinine based EGFR is what's typically reported on routine chemistries and that's suitable for most people. You know, it's easy, it's cheap, it's available, and that creatinine basically gets converted into this EGFR based off of, you know, a variety of available equations, but most commonly used now is the CKD EPI 2021 equation that doesn't include a race coefficient. And again, it's suitable for most folks, but it's less reliable at the extremes of muscle mass, which aren't uncommon. So patients with high muscle mass can overproduce creatinine and can basically show up with an elevated creatinine not related to their kidney disease. And the opposite can happen as well, where a patient with low muscle mass or disease related sarcopenia, for example, can have underproduction of creatinine, which can mask the degree of kidney disease that they have. We also know that certain medications can prevent secretion of creatinine and increase creatinine unrelated to kidney function. So the trimethoprim element of trimethoprim sulfa is a classic example. But more and more agents are falling into this category. So newer cancer agents as well as some elements of antiretroviral therapy. So to circumvent that, we also have cystatin C, which is a serum biomarker that's available to get around these issues. It has its own set of pitfalls. However, it can be included along with creatinine to best assess someone's estimated glomerular filtration rate. So for patients who have perhaps disease that places them at the extreme of muscle mass, using both statin C and creatinine can give you the best sense of what their true kidney function is like.
