CKD and the Kidney Tests Every Person With Diabetes Should Get
Chronic kidney disease (CKD) is a serious complication of diabetes. As the kidneys fail, the body's ability to remove waste products and excess liquid from the blood fails too. This can lead to swelling in the body, mineral imbalances, high blood pressure, stroke, heart attack, and, ultimately, death.
The earlier kidney problems are identified, the better the chance of treating the problems and limiting damage. For this reason, people living with diabetes should have their kidney health examined as part of their annual checkups.
Lab tests to measure kidney function
Current care standards call for both urine and blood tests to measure the current state of kidney function. Both urine and blood samples can easily be collected simultaneously as other annual lab tests.1,2
Urine albumin-to-creatinine ratio
UACR, or urine albumin-to-creatinine ratio, is determined from a urine sample. The UACR is calculated based on the amount of albumin and creatine present in the urine. Albumin is a type of protein. When there are high amounts of albumin in urine, it can point to kidney problems.
Creatinine is a waste product that comes from normal wear and tear on the muscles in the body. The UACR is calculated based on the ratio of albumin to the amount of creatinine in the urine. A UACR result of less than 30mg/g is generally considered normal. A higher reading indicates possible kidney damage.
Estimated glomerular filtration rate
eGFR, or estimated glomerular filtration rate, is based on a blood sample. The GFR is calculated based on the amount of creatinine found in the blood, adjusting for the person's age, gender, and race. Age and body size influence creatinine levels, so normal eGFR levels vary from person to person. In general, an eGFR below 60 is considered an indication of reduced kidney function.
A call for updated kidney testing practices
The National Institutes of Health (NIH), National Kidney Foundation, American Society of Nephrology, and numerous medical establishments across the United States call for a change in how the eGFR is calculated to eliminate the racial bias implicit in how creatinine is currently measured.
How creatinine is measured assumes that Black people (universally) have higher muscle mass than non-Black people. Based on this assumption, creatinine levels are automatically labeled as higher than a non-Black person at the same age — regardless of the person's actual muscle mass. This bias puts people at risk of misdiagnosis.
Proposals for eliminating racial bias
Currently, there are 2 proposals for eliminating this racial bias in kidney testing. The NIH proposes that measuring creatinine be replaced with a cystatin C blood lab test. The results from a cystatin C test do not vary based on the person's race.3
A task force convened by the National Kidney Foundation and American Society of Nephrology has made 3 recommendations for immediate implementation. Along with supporting the switch to cystatin C, the task force calls for implementing a different algorithm for calculating creatinine that does not include race as a factor, and for research on new methods to calculate eGFR based on new endogenous filtration markers that don't include race as a factor.4
Monitor your kidney health yearly
To reduce the risk of misdiagnosis, people may want to discuss the available alternatives with their healthcare provider and determine the best kidney testing option for them. Kidney disease can develop slowly and have few noticeable symptoms.
Living with diabetes is a major risk factor for developing kidney problems, along with high blood pressure, obesity, and aging. The most effective way to monitor kidney health and identify possible issues early on is to get tested every year and monitor the results over time.
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