eGFR and African Americans: What Changed in Kidney Testing

The estimated glomerular filtration rate (eGFR) is a vital test in assessing kidney function and diagnosing kidney disease. For many years, the calculation for eGFR included a specific adjustment for people identified as African American. However, growing understanding of health disparities and ongoing research have prompted significant changes in how eGFR is used for African American individuals. This article explores how eGFR works, why African Americans face higher risks for kidney disease, the impact and controversy of race in eGFR calculations, and what new guidelines mean for patients and clinicians.

What Is eGFR?

The estimated glomerular filtration rate (eGFR) is a blood test used to assess how well the kidneys are filtering waste products from the blood. The test provides a numerical value that helps clinicians gauge kidney health and stage chronic kidney disease (CKD).

• GFR (“glomerular filtration rate”) is the amount of blood filtered by the glomeruli, the tiny filters in the kidneys, each minute.
• eGFR is an estimate based on a blood creatinine test, age, sex, and, until recently, race.
• Creatinine is a waste product produced by muscles and normally filtered out by healthy kidneys. Higher blood creatinine indicates reduced kidney function.

Because direct measurement of GFR is impractical outside of a research setting, doctors calculate eGFR using mathematical equations.

How eGFR Is Measured and Interpreted

Key steps and facts about eGFR testing and score interpretation:

• Blood is drawn to measure creatinine levels.
• eGFR equations use:
  • Serum creatinine
  • Age
  • Sex
  • Race (in legacy equations)
• Normal eGFR values range from 90 to 120 mL/min/1.73m² in healthy adults, but values decline with age.
• Interpreting eGFR:
  • eGFR 60 or higher: normal or near-normal kidney function
  • eGFR below 60: possible kidney disease
  • eGFR below 15: kidney failure or end-stage renal disease

The Historical Role of Race in eGFR Calculations

For decades, most laboratories in the United States used an eGFR equation that included a “race correction” for people identified as African American. This adjustment was based on flawed assumptions that African Americans, as a group, have higher muscle mass and thus produce more creatinine. As a result:

• African Americans were given eGFR values up to 16% higher than non-Black individuals with the same lab results and demographics.
• This adjustment could result in delayed diagnosis or referral for kidney disease care, fewer being listed for transplants, and less aggressive early interventions.
• It also failed to account for the vast biological and social diversity within the African American community.

Problems with the race coefficient:

• The science behind the adjustment wasn’t robust and considered race a biological rather than a social construct.
• Recent studies showed that using self-identified race in medical algorithms could contribute to health inequities and worsen systemic disparities.

Recent Changes: Moving Beyond Race-Based eGFR

Responding to concerns from nephrologists, patient advocates, researchers, and national organizations, leading groups such as the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) launched an initiative to review and revise eGFR equations. As of 2021:

• The new CKD-EPI 2021 Creatinine Equation removed race as a variable, offering a “race-neutral” calculation.
• This equation improves equity and ensures that kidney disease is detected and managed based solely on clinical data, not presumed group characteristics.

Some guidelines also suggest using cystatin C, another blood marker, for a more accurate and unbiased assessment.

Why the Switch Matters

• More timely kidney disease diagnosis and intervention for African Americans and others who may have had their risks underestimated.
• Addresses structural racism in healthcare tools.
• Encourages focus on individual, not population-level, assessment.

Why Are African Americans at Higher Risk for Kidney Disease?

Statistics show that people identified as African American are about three times more likely than non-Black Americans to develop chronic kidney disease or experience kidney failure. Contributing factors include:

• Genetics, including variants of the APOL1 gene more commonly found in people of African ancestry, which may increase risk of certain kidney conditions.
• Higher rates of conditions that damage kidneys, such as diabetes and high blood pressure.
• Inequities in access to health care, preventative services, and timely treatment.
• Social determinants of health — including economic factors, education, and neighborhood environments — that shape risk exposures and outcomes.

Symptoms and Signs of Chronic Kidney Disease (CKD)

Chronic kidney disease often develops slowly and silently. Many people have no symptoms until significant damage has occurred. Common warning signs include:

• Swelling in the legs, ankles, or feet
• Chest pain
• Fatigue or weakness
• Loss of appetite
• Nausea or vomiting
• Itching or numbness
• Increased or decreased urination
• Headaches
• Dry or itchy skin

When Is an eGFR Test Done?

An eGFR test is commonly ordered when:

• Routine health checks for individuals with risk factors (such as diabetes, high blood pressure, or a family history of kidney disease)
• Confirming suspected or early kidney disease
• Monitoring disease progression
• Assessing suitability for certain medications
• Evaluating kidney potential in living organ donors
• Deciding eligibility and timing for dialysis or transplantation

How Are eGFR Results Used?

Doctors use eGFR results to:

• Diagnose chronic kidney disease and stage its severity
• Develop a treatment plan based on the stage
• Refer to a nephrologist (kidney specialist)
• Adjust doses for medicines excreted through the kidneys
• Assess the need for kidney replacement therapies (dialysis or transplant)

eGFR and Kidney Disease Staging Table

What Should African Americans Know About Kidney Risk?

• Younger and older adults are at risk — kidney disease is not just a disease of aging.
• Regular screening is crucial, especially for those with high blood pressure, diabetes, or a family history of kidney failure.
• Stay informed about new, equitable approaches to kidney function testing and care.
• Actively discuss your risk and eGFR results with your doctor.
• Seek culturally competent care and support services when possible.

Reducing Kidney Disease Risk: Steps You Can Take

• Maintain healthy blood pressure through diet, exercise, and medications if needed.
• Control blood sugar if you have diabetes.
• Eat a kidney-friendly diet: Limit salt, processed foods, and excess protein.
• Exercise regularly to help manage weight and cardiovascular risk.
• Don’t smoke, as tobacco speeds kidney damage.
• Stay hydrated, unless otherwise directed by your provider.
• Keep up with regular medical appointments and recommended lab tests.

Genetics, Ancestry, and Other Factors

Recent research has also shown:

• Genetic variants, like those affecting the APOL1 gene, increase risk of some serious kidney diseases in people of African ancestry. However, these genetic factors are not universal in all African Americans.
• Environmental, socioeconomic, and lifestyle factors remain powerful determinants of kidney health outcomes.
• The definition of race in science and medicine is complex; more precise assessments may one day include individual-level genetics or biomarkers rather than broad racial categories.

Changing Practices and Ongoing Advocacy

• Most major US health systems and laboratories are transitioning to race-neutral eGFR reporting.
• Professional guidelines now provide more equitable, accurate care for all people with potential kidney disease.
• Advocacy organizations encourage ongoing review of medical algorithms for all forms of bias.

Frequently Asked Questions (FAQs)

Q: Why did eGFR equations include race in the first place?

A: Early eGFR research used datasets showing, on average, higher serum creatinine in African Americans and assumed this was due to higher muscle mass. The equations included a “race coefficient” to adjust values upward for self-identified African American patients. However, this assumption oversimplified complex genetic and environmental differences and was not scientifically robust.

Q: How does excluding race affect kidney disease diagnosis for African Americans?

A: Removing the race adjustment can result in lower eGFR scores for African Americans with the same laboratory results. This can prompt earlier detection, more timely specialist referrals, and greater eligibility for transplant evaluation, helping address long-standing disparities in kidney care.

Q: What if my eGFR falls below 60?

A: An eGFR below 60 mL/min/1.73m² may indicate reduced kidney function and possible chronic kidney disease. Your healthcare provider will confirm the diagnosis, determine the stage, and plan appropriate monitoring or treatment. In many cases, kidney function decreases slowly, so ongoing monitoring is critical.

Q: Should I ask for cystatin C testing in addition to creatinine?

A: Cystatin C is an alternative blood marker not influenced by muscle mass or race. In some cases, measuring both creatinine and cystatin C can provide a more accurate estimate of GFR. Discuss with your provider whether this is appropriate for your health situation.

Q: What resources are available for culturally competent kidney care?

A: Many large hospitals and organizations like the National Kidney Foundation offer information, support, and referrals to providers with experience in caring for African American individuals and those at higher risk of kidney disease.

Key Takeaways

• eGFR is vital for detecting and managing kidney disease.
• Race-based adjustments have been phased out in favor of equitable, data-driven approaches.
• African Americans are at higher documented risk for CKD — but risk can be reduced through proactive health management.
• Continuous advocacy and improved testing can help narrow disparities in kidney health outcomes.