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Instant Insights: Kidney Profile and eGFR with creatinine and cystatin-C (7 min)
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Welcome to Healthier World with Quest Diagnostics. Our goal is to prompt action from.
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Insight as we keep you up to.
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Date on current clinical and diagnostic topics in cardiovascular, metabolic, endocrine and wellness medicine.
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Welcome to a special episode designed to give you instant insights into the utilization of the kidney profile. I'm Dr. Mason Latsko, a researcher by training with a passion for learning, and I'm here with some information on how the Kidney Profile aligns with the CKD guidelines that were updated in 2024 by Kidigo, which stands for Kidney Disease Improving Global outcomes. More than 1 in 7 U.S. adults are estimated to have CKD and early stages of CKD are often silent. In fact, 90% of people who have CKD don't know they have it. The majority of patients are missed during these early stages when the condition can actually be managed and prevented using diet, lifestyle and medications. The top two risk factors for CKD are hypertension and diabetes, so screening these two populations is crucial in the proper assessment of ckd. In fact, screening hypertensive and diabetic individuals for CKD is a quality metric set forth by the Healthcare Effectiveness Data and Information Set or given that 10 to 12% of people have diabetes and approximately 50% have hypertension, screening for CKD should be done in approximately 60% of our population. But many of these high risk individuals are not receiving guideline recommended screening. That's why Quest offers the Kidney Profile, which includes the two guideline recommended tests for staging CKD and meets the quality metrics needed for HEDIs. CKD can be caused by the presence of kidney damage which is assessed using a urine albumin creatinine ratio or by decreased function which is assessed using an egfr. Let's first start by talking about kidney damage. We can think of this as structural damage to the kidneys. The kidney functions to filter out blood and allow proteins that should be in the blood to remain in the blood while pulling out proteins that should not be in the blood to be excreted in the urine. So if your kidneys have structural damage, proteins that don't typically leak out into the urine will be found in the urine. The component of the kidney profile that assesses structural damage is called a urine albumin creatinine ratio. Importantly, a lot of providers are leaving this out when assessing patients for ckd, so essentially missing half the story by excluding this test. So that's structure. What about function? To test for functional damage of the kidneys, we measure what we call an egfr, which stands for estimated glomerular filtration rate. An EGFR is a blood test that measures how well your kidneys filter out proteins that should be filtered out. So when the kidneys are functioning well, protein levels in the body are just right and an EGFR can be estimated using two proteins. Most of the time an EGFR is calculated based on a protein called creatinine and creatinine is a waste product in the body that comes from the breakdown of muscle tissue and the digestion of proteins from food. Therefore, there are certain populations that don't have an accurate EGFR based on creatinine, such as those with low or high meat diets or elder individuals or those with low muscle mass such as sarcopenia for example, and of course those with high muscle mass like bodybuilders. In many cases, the serum creatinine can underestimate CKD staging and underestimates the associated cardiovascular risk with it. An EGFR can also be calculated based on a different protein called a cystatin C, and cystatin C is produced by all cells in our body. You may be most familiar with the cystatin C as a follow up for individuals who fall into a ckd category if stage 3A based on the 2012 guidelines, cystatin C isn't impacted by the same factors that creatinine is, such as muscle mass or age. However, cystatin C isn't a perfect marker either as it can be influenced by untreated thyroid conditions, steroids and even certain cancers. So since neither protein is the perfect solution for an EGFR by itself, the CKD guidelines from 2024 announced a new estimation for EGFR using both creatinine and cystatin C. Using this new combined EGFR is a more reliable estimate of kidney function. It improves risk assessment and allows for early detection of ckd. Not only does the combined EGFR better predict risk for CKD, but the 2024 guidelines highlight how using a combined EGFR with creatinine and cystatin C better predicts risk for many other cardiometabolic conditions as well. These conditions include all cause mortality, cardiovascular mortality, end stage renal failure, myocardial infarction, stroke, afib, peripheral artery disease, acute kidney injury and progressive ckd. Let's walk through this through the lens of a provider. So if a provider is interested in assessing for ckd they should order a kidney profile which is a urine albumin creatinine ratio and an EGFR based on creatinine if the results show that the patient falls within a CKD stage of 3a or greater, that's an EGFR less than 60 or an elevated urine albumin creatinine ratio greater than 30, those patients should follow up with an EGFR using creatinine and cystatin C. Additionally, if the patient has a condition where the EGFR protein may be impacted, these are also patients who should be getting the EGFR based on both creatinine and cystatin C. That concludes your instant insight into the utilization of the Kidney Profile for proper CKD assessment. The 2024 guidelines emphasize the importance of using both creatinine and cystatin C in estimating an EGFR in high risk individuals in order to provide a more refined risk assessment for CKD and other cardiometabolic conditions. By adopting these testing solutions, clinicians will be able to provide comprehensive management to address both kidney health and overall cardiovascular well being.
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That's a wrap on this episode of Health World with Quest Diagnostics. Please follow us on your favorite podcast app and be sure to check out Quest Diagnostics Clinical Education center for more resources, including educational webinars and research publications. Thank you for joining us today as we work to create a healthier world, one life at a time.