Doctors use estimated glomerular filtration rate (eGFR) scores to measure kidney functioning. African American people typically have higher eGFR scores than people of other ethnicities.

People with chronic kidney disease (CKD) have bodies that are unable to filter their blood correctly due to kidney damage. This causes symptoms that include:

Diabetes, high blood pressure, heart disease, and a family history of kidney failure are the main causes of CKD. The Centers for Disease Control and Prevention (CDC) estimate that more than 1 in 7 adults in the United States have CKD.

Doctors may conduct several tests to check on health and disease progression in people with CKD.

This article discusses eGFR, which is a test of kidney functioning, in more detail. It focuses on African American people, the scores they may receive, and why.

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The glomerular filtration rate (GFR) is a measure of how well the kidneys are working. It tells doctors how much blood passes through tiny filters in the kidneys each minute. These kidney filters are called glomeruli, and they remove waste from the blood. However, GFR is difficult to measure directly.

Instead, doctors can use a mathematical equation to predict eGFR from a blood sample. This involves measuring the amount of creatinine, which is a waste product that the kidneys help remove, in the blood. High creatine levels indicate worse kidney functioning.

The equation also takes into account other factors that may influence kidney functioning, including:

  • age
  • sex
  • ethnicity

African American people have an increased risk of kidney disease due to higher rates of diabetes, high blood pressure, and heart disease. They also typically have elevated creatinine levels in their blood. This means that they often have higher eGFR scores than people from different ethnic backgrounds.

It is important to mention that these factors are likely due, at least in part, to health inequities and structural racism in the medical community.

Because of these health concerns, some calculations to determine eGFR include race or ethnicity as a factor. This can help the eGFR score provide a more reliable indication of kidney functioning to guide diagnosis and treatment decisions.

However, laboratories are not always aware of the person’s ethnicity when they receive a blood sample. This is why they typically provide separate results for African American and non-African American people in their reports.

The National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) formed a joint task force in 2020 to review the use of race and ethnicity in these calculations. They proposed a new approach to estimating eGFR in September 2021.

Until September 2021, the two most common equations for estimating eGFR were the Modification of Diet in Renal Disease (MDRD) equation and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.

Both equations involve taking a blood sample from a person’s arm to send off for testing. Scientists then use the MDRD or CKD-EPI equation to calculate the person’s eGFR score. These equations take into account a person’s creatinine levels, age, sex, and ethnicity.

In September 2021, the NFK and ASN task force released a report suggesting that these equations overestimated GFR in African American people and, to a lesser extent, non-African American people. For this reason, they recommend using a new 2021 CKD-EPI creatinine equation to calculate eGFR, which excludes ethnicity as a factor.

The task force also recommended using cystatin C to calculate eGFR. Cystatin C is a protein that the kidneys filter out of the blood.

The NKF aims to keep assessing these equations to ensure that they are as accurate as possible.

The following eGFR results indicate how well the kidneys are functioning:

  • An eGFR score of 60 or higher indicates normal functioning.
  • An eGFR score of under 60 may indicate kidney disease.
  • An eGFR score of under 15 may indicate kidney failure.

A healthcare professional can use these results to make several decisions, including:

  • diagnosing kidney disease
  • confirming that kidney function is normal for a potential kidney donor
  • deciding on a kidney disease treatment plan
  • making sure that someone uses the correct dosage and type of medication
  • determining whether or not someone needs a nephrologist, or a kidney specialist
  • deciding when to start dialysis
  • examining the need for a kidney transplant

According to the NKF, African American people are three times more likely to develop kidney disease than non-African American people. African American people also make up over 35% of people in the U.S. who receive dialysis for kidney failure.

The NKF states that African American people should be aware of their increased kidney disease risk and its risk factors, which include high blood pressure, diabetes, and heart disease.

It recommends that African American people visit a doctor or clinic regularly, if possible, to check their blood sugar level, blood and urine pressure, and kidney function.

African American people can use the following sources to find culturally competent healthcare professionals.

The Black Health Matters Nephrologist Guide

Black Health Matters provides a wide range of information about health and well-being tailored to African American people.

Its website includes a list of recommended nephrologists for African American people. The page also offers advice to help people find the right nephrologist for them.

Black Doctors USA

Black Doctors USA states that racial biases cause an increased risk of chronic conditions in Black and other marginalized communities. The group aims to ensure that people in these communities have access to doctors who understand these biases.

Black Doctors USA provides a service on its website for finding Black doctors, including kidney specialists, in the local area.

CKD causes problems with how the kidneys function. This means that they cannot properly filter waste from the blood.

Doctors use measures of GFR as indicators of kidney functioning. However, the procedure is difficult to administer, so they typically use eGFR instead.

To do this, they take a blood sample to measure the amount of creatinine in the blood and use an equation to calculate eGFR. These equations have traditionally included the person’s age, sex, and ethnicity. However, updated equations now exclude race and ethnicity when calculating eGFR.