How Is an EGFR Blood Test Used to Diagnose or Monitor Kidney Disease?

If you have high blood pressure, diabetes, or other conditions affecting kidney function, your doctor may order a test to measure your eGFR.

Traditionally, GFR has been estimated by an injection of a substance into the bloodstream that is later measured in a 24-hour urine collection. 

Stage of Kidney Disease

A blood test called an eGFR (estimated glomerular filtration rate) is often used to diagnose or monitor kidney disease. The eGFR is based on creatinine and other information about your health, such as age and gender. If you have kidney disease, your eGFR will change as it worsens.

In general, a GFR number of 60 or higher is considered normal. But a GFR lower than 15 may mean your kidneys are failing. If you have a GFR of 15 or less, your doctor will likely recommend dialysis or a kidney transplant.

Your EGFR blood test can also be affected by certain medications you take. These include cisplatin and gentamicin, which increase your level of creatinine.

When your eGFR is lower than 60, your doctor may refer you to a nephrologist who specializes in treating kidney problems. Your doctor may recommend treatments to slow the progression of your kidney damage, such as lowering your blood pressure and controlling your diabetes.


When your kidneys work properly, toxins (waste) are removed from the blood. This happens through tiny filters called glomeruli in your kidneys. When your glomeruli aren’t working as well, the toxins may build up in your blood, causing damage to your kidneys.

A test that helps doctors detect kidney problems is an estimated glomerular filtration rate or eGFR. It measures how much blood the kidneys filter each minute based on your body size. This test can help identify a problem before symptoms develop.

The test also determines how far along you are in the kidney disease process and whether you are at risk for developing kidney failure. Your healthcare team will calculate your eGFR based on the results of another test, most likely your blood creatinine level.

It’s important to remember that eGFR tests are not 100% accurate, so you’ll have to see your doctor to discuss your results with them. Your provider can also help you understand the stages of kidney disease that match your eGFR and how these stages affect your treatment options.

Usually, when the eGFR is below 60 mL/min per 1.73 square meters of body surface area, it’s a sign that you have kidney disease and should talk to your doctor as soon as possible. Your provider can also give you more specific information about your results, taking into account your age, weight, health history, and other factors.

An eGFR test can be done at your doctor’s office or home with an at-home test kit. At-home tests typically take a few days to get results, but you can check the status of your test on a website or smartphone app.

A normal eGFR is about 90 to 120 mL/min per 1.73 square meters of body surface area but can vary among people of different ethnicities and other health conditions. The higher the number, the better your kidneys are working.


A healthcare professional usually diagnose kidney disease after a patient has had a series of blood tests over several months. These tests are to monitor the eGFR blood test, which is an estimation of how well your kidneys filter your blood and can be used to detect kidney damage.

The eGFR is also used to assess existing kidney disease severity (stage). This is useful when planning management and monitoring treatment.

An eGFR blood test is a quick and easy way to determine how well your kidneys function. It measures your glomerular filtration rate, the volume of blood filtered per minute by your kidneys. This number is based on a formula that considers your age, sex, and a test called creatinine.

This value is usually quoted as a percentage of normal. This helps make the results more accessible to patients and their families.

Some people may be asked to have an eGFR blood test as a preventative measure, especially those at risk of developing kidney disease or whose family history is linked with the condition. This is because it is important to catch kidney problems before they get worse so they can be treated before they lead to further complications.


A test measuring how well your kidneys filter blood is known as a GFR (glomerular filtration rate) or eGFR. This test is a good indicator of kidney function and helps determine your kidney disease stage.

Your healthcare professional may order a GFR lab test to diagnose chronic kidney disease or to monitor your kidney health. It can be done at a hospital, doctor’s office, or home.

The GFR tests how well your kidneys filter waste products from the blood, like excess fluid and creatinine. It is usually done by taking blood and urine samples and using a special formula to estimate how efficiently your kidneys work.

Several different equations can be used to calculate your eGFR. Some consider your body size, while others use a formula that considers how many fluids your kidneys filter out per minute.

In some cases, your eGFR test results can be more accurate if you are tested more often than once a year. These are called serial eGFR measurements and can help your doctor determine if you are getting worse or better over time.

There are also new ways to monitor your eGFR, such as a smartphone attachment that works with an app on your mobile device. This device measures the level of a protein in your blood called albumin, which can indicate the health of your kidneys.

Richard Brown


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