The Estimated Glomerular Filtration Rate (eGFR) test measures how well your kidneys are functioning. It is a blood test that estimates the amount of blood filtered by the glomeruli, the tiny filters in the kidneys. The eGFR test considers a person's age, sex, race, and blood creatinine level to calculate the estimated kidney function. The body produces creatinine as a byproduct of muscle metabolism, and the kidneys are responsible for removing it from the blood. The eGFR test is considered more accurate than a simple blood creatinine test because it accounts for these additional factors. A normal eGFR is typically above 90 mL/min/1.73m2, and a value below this indicates some level of kidney damage. The eGFR is reported in mL/min/1.73m2, which is a measure of the amount of blood filtered by the kidneys per minute normalized to a standard body surface area. 

What is an Estimated Glomerular Filtration Rate test? 

The Estimated Glomerular Filtration Rate (eGFR) test measures how well your kidneys are functioning. It is a blood test that estimates the amount of blood filtered by the glomeruli, the tiny filters in the kidneys. The eGFR test considers a person's age, sex, race, and blood creatinine level to calculate the estimated kidney function. The body produces creatinine as a byproduct of muscle metabolism, and the kidneys are responsible for removing it from the blood. The eGFR test is considered more accurate than a simple blood creatinine test because it accounts for these additional factors. A normal eGFR is typically above 90 mL/min/1.73m2, and a value below this indicates some level of kidney damage. The eGFR is reported in mL/min/1.73m2, which is a measure of the amount of blood filtered by the kidneys per minute normalized to a standard body surface area. 

What is the purpose of an Estimated Glomerular Filtration Rate test? 

The purpose of the Estimated Glomerular Filtration Rate (eGFR) test is to assess how well the kidneys are filtering waste from the blood. This test measures the glomerular filtration rate, which is the rate at which blood flows through the tiny filters in the kidneys called glomeruli. The eGFR test helps healthcare providers evaluate kidney function and detect early signs of chronic kidney disease (CKD). The eGFR test is an important tool for healthcare providers to assess kidney function and diagnose CKD. If the eGFR result indicates decreased kidney function, additional tests may be ordered to determine the underlying cause and to develop a treatment plan. Overall, the eGFR test helps healthcare providers monitor kidney health and prevent further kidney damage. 

What does the Estimated Glomerular Filtration Rate test diagnose? 

The Estimated Glomerular Filtration Rate (eGFR) test is used to diagnose and monitor kidney disease by assessing how well the kidneys are functioning. Here are a few other things the eGFR test diagnoses: 
 

• Kidney function: The eGFR test measures the rate at which blood flows through the tiny filters in the kidneys called glomeruli. A reduced eGFR value indicate that the kidneys are not functioning properly. 
• Chronic kidney disease (CKD): The eGFR test is used to diagnose and monitor CKD, a progressive condition in which the kidneys stop functioning over time. CKD can lead to other health problems if left untreated. 
• Early detection: The eGFR test is a valuable tool for detecting kidney disease in its initial stages when treatment is most effective. It can help healthcare providers identify patients at risk for kidney disease and develop a treatment plan to slow or prevent further damage to the kidneys. 
• Risk factors: The eGFR test can help healthcare providers identify risk factors for kidney disease, such as high blood pressure, diabetes, and a family history of kidney disease. Early identification of risk factors can help prevent or delay the onset of kidney disease.
   

Preparation and procedure required for an Estimated Glomerular Filtration Rate test 

Preparation for an Estimated Glomerular Filtration Rate (eGFR) Test: 
 

• Fasting: There is no requirement for fasting before the eGFR test. However, some healthcare providers may suggest fasting if other blood tests are being done at the same time. 
• Medications: Inform your healthcare provider about any medications you are taking, including over-the-counter medications and supplements, as some of them can affect the test results. Your healthcare provider may advise you to stop taking certain medications before the test. 
• Hydration: Drink enough water to stay hydrated, as dehydration can affect the accuracy of the eGFR test results. 
   

Procedure for an Estimated Glomerular Filtration Rate (eGFR) Test: 
 

• Blood sample: The eGFR is a blood test that requires a sample of blood to be drawn from a vein in your arm. The healthcare provider will clean the area with an antiseptic and insert a needle into your vein to collect the blood sample. 
• Post-test: After the blood sample is collected, a bandage will be placed over the needle insertion site. You may experience mild discomfort or bruising at the site of the needle insertion, which will resolve in a few days. 
   

The eGFR test is a simple blood test that requires minimal preparation and can be done in a healthcare provider's office or a laboratory. It is a routine test commonly done as part of a regular physical exam or as a follow-up to other tests indicating kidney problems. 

After the test 

After an Estimated Glomerular Filtration Rate (eGFR) test, the blood sample is sent to a laboratory for analysis. The results are available within a few days, and your healthcare provider will review the results with you. 

If the eGFR value is normal, no further treatment may be required. If the eGFR value is below normal, your healthcare provider may recommend additional tests to determine the underlying cause of kidney dysfunction and develop a treatment plan. 

It is important to follow your healthcare provider's instructions regarding any further testing or treatment. If you have been diagnosed with chronic kidney disease (CKD), your healthcare provider may recommend lifestyle changes such as following a healthy diet, quitting smoking, and exercising regularly. They may also prescribe medications to control blood pressure and reduce protein in the urine, which can help slow the progression of CKD. 

Understanding the Estimated Glomerular Filtration Rate Test results

The eGFR test measures the rate at which blood is filtered through the kidneys, and the results are expressed in milliliters per minute per 1.73 square meters (mL/min/1.73m²). 

The interpretation of eGFR results may vary slightly depending on the laboratory performing the test and the individual's age, gender, and race. In general, the following ranges are considered normal: 
 

• eGFR greater than or equal to 90 mL/min/1.73m²: normal kidney function 
• eGFR between 60 and 89 mL/min/1.73m²: mildly reduced kidney function 
• eGFR between 30 and 59 mL/min/1.73m²: moderately reduced kidney function 
• eGFR between 15 and 29 mL/min/1.73m²: severely reduced kidney function 
• eGFR less than 15 mL/min/1.73m²: kidney failure 
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Depending on the results of the Estimated Glomerular Filtration Rate (eGFR) test, several steps may be taken: 
 

• Normal eGFR results: If the eGFR value is within the normal range, no further action may be required. However, it is important to regularly monitor your kidney function, especially if there are risk factors for kidney disease. 
• Low eGFR results: If the eGFR value is below normal, it may indicate reduced kidney function or chronic kidney disease (CKD). Your healthcare provider may recommend additional tests, such as a urine test or imaging studies, to determine the underlying cause of kidney dysfunction. Treatment options may include lifestyle changes, medications, or dialysis. 
• Trending eGFR results: If eGFR results are trending downwards over time, it may indicate declining kidney function or progression of CKD. Your healthcare provider may recommend additional tests, treatment adjustments, or referral to a nephrologist (a specialist in kidney disease) for further evaluation. 
• High eGFR results: If the eGFR value is higher than normal, it may indicate that the test results are not accurate, or it may be a sign of kidney damage caused by certain medications, kidney stones, or other conditions. Your healthcare provider may recommend additional testing or medication adjustments.