EGFR (Estimated Glomerular Filtration Rate)

The estimated glomerular filtration rate (eGFR) test, also known as the estimated GFR test, which measures how well your kidneys are filtering blood.

Glomeruli are microscopic filtering structures in the kidneys that help remove waste from the bloodstream. The eGFR test measures how much blood flows through the glomeruli each minute. In conditions such as chronic kidney disease, kidney failure, and sudden kidney injury, eGFR may decrease. Doctors use this test to monitor disease progression and assess whether treatments are working.

You may be advised to get the eGFR test if you are experiencing the following symptoms of chronic kidney disease:

• Nausea
• Headache
• Unexplained weight loss
• Itching and dry skin
• Fatigue and weakness
• Ankle swelling
• Decreased urine output
• Loss of appetite
• Shortness of breath

The test is also strongly advised for the following categories of people:

• Individuals who have been diagnosed with chronic kidney disease (CKD) – The eGFR test can be used to check how much the disease has advanced.
• Individuals with diabetes – In patients with diabetic, small blood vessels in the kidneys are damaged, making them more likely to develop kidney disease.
• Individuals with urinary tract infection (UTI) – The test is advised for complicated or recurrent UTIs and UTIs where kidney involvement is suspected.
• Individuals with high blood pressure – High blood pressure can harm the small blood vessels in your kidneys, which can result in kidney disease and failure.
• Family history of CKD – Having a family history of CKD also increases the risk of developing the disease.
• Individuals at high risk of kidney conditions – These include individuals with conditions such as cardiovascular disease, autoimmune diseases that affect the kidneys, and older adults.

The eGFR test can be used along with other tests to help diagnose and monitor certain conditions, such as:

• CKD – This is a condition in which your kidneys cannot filter blood properly, leading to the accumulation of waste in the body.
• Kidney failure – In this condition, the kidneys are damaged, and harmful waste products build up in the body.
• Acute kidney injury (AKI) – This happens when the kidneys stop working or become damaged within a very short period of time.

What to Expect Before the EGFR Test

No fasting is required for a standalone EGFR test. You can eat and drink normally. However, if it is part of a broader package that includes fasting tests, your doctor may advise fasting for 8-12 hours. Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily raise EGFR levels and affect interpretation. Always inform your doctor about any ongoing medications.

What to Expect During the Blood Collection

A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute.

What to Expect After the EGFR Test

A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and rest for a few minutes.

In the eGFR test, the primary parameter being measured is:

• The estimated glomerular filtration rate.

The eGFR test normal range is given in the table below:

Note: Normal values may differ slightly between laboratories. A doctor should always interpret the results. eGFR should always be interpreted together with urine albumin and clinical findings.

The table below explains what the eGFR test results may indicate:

Note: A decrease in eGFR may indicate kidney disease. Your doctor will diagnose your condition depending on your medical history, symptoms, and other blood tests.

The eGFR test is a simple blood test. However, it has some risks and limitations that should be known:

Risks:

Although it is a simple blood test, it has some minor risks, as with any other blood test. The blood collection process can sometimes cause bleeding, bruising, or mild soreness as side effects. However, most of these disappear quickly.

Limitations:

• The eGFR test is a complicated test. The healthcare providers need to know your age and sex to calculate your eGFR.
• The creatinine test is needed along with the eGFR test to accurately calculate the GFR.

Depending on your medical condition and symptoms, you may be advised to get additional medical tests, such as:

• Protein in urine test
• Urine albumin to creatinine ratio (uACR) test
• Blood urea nitrogen test
• Serum creatinine test
• Albumin test
• Calcium test
• Complete blood count
• Electrolytes test
• Magnesium test
• Phosphorus test