EGFR Blood Test

What is an EGFR Blood Test?

In our kidneys, we have these small filters called glomeruli. Their function is to assist the kidneys with getting rid of toxins in our blood.

When medical professionals discuss estimated glomerular filtration rate, or EGFR for short, they refer to the amount of blood the glomeruli can filter every minute. They use this measurement to monitor the kidneys and determine any potential kidney problems a patient has.

They measure this by conducting EGFR Blood Tests (commonly called a serum creatinine test), often part of metabolic panels, which are comprehensive assessments that examine the functioning of the kidneys and liver, fluid balance, and electrolyte levels.

If a patient has kidney problems, there is a good chance that the glomeruli’s filtering capabilities are negatively impacted, which means they don’t filter toxins at the rate they usually do.

This test is one of the go-to tests for patients who present themselves with the following symptoms:

• They feel weak and fatigued
• They have shortness of breath
• They pee frequently
• Their pee is foamy or has blood
• They feel nauseous and vomit from time to time
• Their ankles, hands, or feet are swollen
• They have muscle cramps and spasms
• Their skin is dry and itchy

How to conduct EGFR Tests

On the part of the patient:

EGFR Blood Tests are not immediately conducted even if patients present themselves with the abovementioned symptoms. They need to discuss the best time to take the test first. The reason for this is that patients need to do the following:

• They need to fast for several hours before taking the test (they can drink fluids, though)
• They need to inform their healthcare providers about any medications, vitamins, and supplements they take because some of them might interfere with the results
• They might need to avoid eating meat the day before the test because studies have indicated the possibility of meat temporarily raising creatinine levels

On the part of the healthcare provider:

Once the patient arrives for the blood test as scheduled, the healthcare professional handling them will conduct the EGFR Blood Test as follows:

• They will have the patient sit down and extend one of their arms forward
• While the arm is extended, the professional will use antiseptic to clean the spot where they will draw blood from
• After cleaning the spot, they will tie a stretchy band above the spot to make the veins more visible
• They will use a collection tube with a needle to get a blood sample from a vein. The patient might feel a bit of pain or discomfort when the needle pierces through their skin
• After drawing enough blood for a sample, they will remove the needle and cover the puncture hole with a cotton ball or bandage to stop any bleeding that occurs
• The professional will send the blood sample to a laboratory to be analyzed

How are the results of an EGFR Blood Test interpreted?

When healthcare professionals measure EGFR, they do so by milliliters of cleansed blood per minute per body surface. This is written as mL/min/1.73m2.

As a reference, the normal levels for EGFR are based on the levels that the National Kidney Foundation established:

• For those aged 20 to 29: 116mL/min/1.73m2
• For those aged 30 to 39: 107mL/min/1.73m2
• For those aged 40 to 49: 99mL/min/1.73m2
• For those aged 50 to 59: 93mL/min/1.73m2
• For those aged 60 to 69: 85mL/min/1.73m2
• For those aged 70+: 75mL/min/1.73m2

Please note that EGFR will decline as we age.

As for reading the results, please refer to these designations by the National Kidney Foundation:

• EGFR of 90+: there is possible kidney damage but the kidney is still functioning normally
• EGFR of 60 to 89: there is kidney damage and a mild loss of kidney function
• EGFR of 45 to 59: there is a mild to moderate loss of kidney function
• EGFR of 30 to 44: there is moderate to severe loss of kidney function
• EGFR of 15 to 29: there is a severe loss of kidney function
• EGFR of less than 15: kidney failure

Depending on the results, healthcare professionals will determine the next set of tests to conduct to confirm the kidney disease and its causes. Treatment will depend on the full results.

When is it best to conduct an EGFR Blood Test?

Examinations for potential kidney disease/kidney failure

As mentioned earlier, EGFR Blood Tests are meant for evaluating patients who might have kidney damage, kidney disease, or kidney failure if they present themselves with symptoms such as weakness, fatigue, frequent urination, nausea, muscle cramps, and muscle spasms, to mention a few.

This test will help professionals determine if they must conduct tests such as urinalyses, CT scans of the kidneys, kidney biopsies, and creatine clearance tests.

Monitoring medication side effects and patient condition

Certain medications might affect the kidneys, especially if the prescribed dosage is not followed, whether on purpose, neglect or by accident. Healthcare professionals might require patients to take routine EGFR Blood Tests to check if the medication they administered and prescribed is negatively impacting the kidneys.

Not only that, but they will use this test to see if kidney function is the same or if it's gradually declining. Healthcare professionals will make adjustments to treatment plans depending on the results.

Evaluating patients before specific procedures

The EGFR Blood Test is also conducted to screen patients if they're healthy enough to undergo specific medical and surgical procedures. Some medications can have adverse effects on the kidney, but these medications might be needed when conducting specific medical or surgical procedures.

If there is already a moderate or severe loss of kidney function due to kidney disease, then they might not be eligible to undergo such procedures.