Estimated Glomerular Filtration Rate (eGFR)

What is Estimated Glomerular Filtration Rate (eGFR) Test?

An Estimated Glomerular Filtration Rate (eGFR) test is a blood test that assesses kidney function by measuring how much blood the kidneys filter each minute. Your kidneys, located on each side of your spine near your waist, contain tiny filtering units called glomeruli. These glomeruli help filter waste and excess fluids from your blood, removing them through urine.

When kidneys are impaired, often due to kidney disease, they cannot filter blood efficiently. A low eGFR may indicate kidney failure, which may require treatments like dialysis or a kidney transplant. The eGFR test serves multiple purposes:

• Screening for kidney disease in people who show no symptoms

• Diagnosing kidney disease in individuals who do have symptoms

• Assessing the stage of kidney disease

• Monitoring people with chronic kidney disease (CKD) to track the effectiveness of treatment

• Checking kidney health for those taking medications that could harm the kidneys

• Evaluating kidney function before starting treatments that could affect kidney health

The eGFR test is an important tool for early detection, diagnosis, and ongoing management of kidney health.

Estimated Glomerular Filtration Rate (eGFR) Test Parameters

The estimated glomerular filtration rate (eGFR) test evaluates one specific parameter: the rate at which the kidneys filter blood, expressed as the amount of blood filtered per minute. 3

The eGFR test serves as an important assessment of kidney function. While the glomerular filtration rate (GFR) can be measured directly, this method is complex and not commonly performed. Instead, estimated GFR is calculated using a blood test that measures creatinine levels, a waste product produced during normal muscle activity. Elevated creatinine levels in the blood can indicate impaired kidney function.

Individual factors such as age, weight, height, and sex, along with creatinine levels, are used in a mathematical formula to calculate eGFR. Since creatinine production varies based on body size, diet, and activity, these additional factors help provide a more accurate estimate.

eGFR can also be calculated using cystatin C, which is a protein produced by cells throughout the body. Unlike creatinine, cystatin C levels are not influenced by muscle mass, age, or diet, making it potentially more accurate for certain individuals. Research is ongoing to explore whether combining creatinine and cystatin C measurements can offer a more comprehensive assessment of kidney health.

Overall, the eGFR test is essential for assessing kidney health and identifying potential issues.

Estimated Glomerular Filtration Rate (eGFR) Test Preparation

Consider the following before scheduling an Estimated Glomerular Filtration Rate (eGFR) test :

• Prerequisites

You do not have to fast before undergoing an eGFR test.

• Best Time to Get Tested

This test can be scheduled at any time of day.

• Who Should Get This Test

Individuals at risk for kidney disease, including those with diabetes, hypertension, or a family history of kidney issues, should get this test.

• Cautions Before Taking This Test

No specific preparation is usually needed before the eGFR test. However, you should consult your doctor before undergoing the test to ensure it is appropriate for your situation.

Why Take the Estimated Glomerular Filtration Rate (eGFR) Test?

The eGFR test is important for identifying early signs of chronic kidney disease (CKD), which often does not have noticeable symptoms in its initial stages. Healthcare providers typically recommend this test for individuals who are at an increased risk of developing CKD. Key risk factors for CKD include:

• Diabetes : A significant contributor to kidney damage over time.

• High Blood Pressure : This condition can strain blood vessels in the kidneys.

• Overweight/Obesity : Excess weight can impact kidney health.

• Age Over 60 : Older adults are at greater risk for kidney-related issues.

• Family History of CKD or Kidney Failure : A genetic predisposition can increase the risk of CKD.

CKD often arises from multiple interconnected factors, including physical health, environmental influences, and social conditions.

When symptoms of CKD manifest, most times CKD is in its later stages. Symptoms that may indicate advancing kidney disease include:

• Frequent or infrequent urination

• Persistent itching

• Unusual fatigue

• Swelling in the extremities (arms, legs, or feet)

• Nausea and vomiting

• Muscle cramps

• Decreased appetite

An eGFR test can help monitor kidney function and detect potential issues before they become more serious.

FAQs on Estimated Glomerular Filtration Rate (eGFR) Test 

1. How much does the Estimated Glomerular Filtration Rate (eGFR) test cost?