Estimated GFR With Cystatin C and Creatinine in Clinical Practice
In this video, Eric Gottlieb, MD, MS, discusses the use of cystatin C vs creatinine to estimate glomerular filtration rate in diverse patient populations and how the use of cystatin C to estimate GFR can impact kidney care delivery.
- Gottlieb ER, Estiverne C, Tolan NV, Melanson SEF, Mendu ML. Estimated GFR with cystatin C and creatinine in clinical practice: a retrospective cohort study. Kidney Med. 2023;5(3):100600. doi:10.1016/j.xkme.2023.100600
Eric Gottlieb, MD, MS, is a hospital medicine physician at Mount Auburn Hospital, an instructor in medicine at Harvard Medical School, and is board certified in nephrology (Cambridge, MA).
Eric Gottlieb, MD, MS: My name is Dr. Eric Gottlieb. I'm a nephrologist in the Boston area and work as a hospital medicine physician at Mount Auburn Hospital in Cambridge.
Consultant360: Please provide an overview of the study “Estimated GFR With Cystatin C and Creatinine in Clinical Practice: A Retrospective Cohort Study.”
Studies showed that cystatin C is generally well correlated with creatinine, which is good because it means that it's an effective and consistent measure that can be used for the estimation of GFR. However, it did show that cystatin C in many patients will give a GFR that is somewhat lower than creatinine, and this can affect chronic kidney disease staging. This is particularly true in patients who are more elderly or have more comorbidities or additional disease processes.
C360: What were the objectives and conclusions of this study?
Dr Gottlieb: With the new GFR formulas, cystatin C is recommended for confirmation of the estimate of GFR that is given by creatinine. And so this suggests that in the near future, cystatin C is going to be used more commonly. And if we're going to use a new test we need to know what to expect, how this is going to change our key metrics for the definition and measurement of chronic kidney disease, and therefore how it may affect clinical care.
C360: How do the results of this study impact clinical practice and affect kidney care delivery?
Dr Gottlieb: Given that this is a test that is growing in popularity and is now recommended, we see there's going to be more and more use in the near future, and a lot more research is needed. First of all in different populations, so this was from one academic medical center in the Northeast and several surrounding primary care clinics. So we need to look at replicating our results in different communities, with different racial, gender, and socioeconomic makeup. Also to do a prospective study. So our study was retrospective, and therefore there's always potential bias, and so it would be important to do a prospective study to confirm and verify our results.
C360: What is next for research on this topic?
Dr Gottlieb: First of all, this supports the use of cystatin C because generally, it does correlate with GFR, but there are key differences as we said, particularly in patients of advanced age and with more comorbidities, and so it's important to use this study to look at this, and then do more exploration to understand how cystatin C is going to affect clinical decision making.
C360: What are the overall take-home messages from the study?
Dr Gottlieb: I think it's just important that people become aware of cystatin C, how it can be used, and consider when and whether this will be appropriate for their patients.