eGFR (Estimated Glomerular Filtration Rate) Biomarker Testing
eGFR estimates how well your kidneys filter blood and helps stage CKD; order through Vitals Vault with Quest labs and PocketMD support.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
Your eGFR (estimated glomerular filtration rate) is one of the most useful numbers on a kidney health report because it summarizes how well your kidneys are filtering blood.
It is not a single substance the lab measures directly. Instead, your eGFR is calculated from your blood creatinine plus your age and sex, using a standardized equation.
Because eGFR can change with hydration, illness, and muscle mass, the most helpful way to use it is in context: your symptoms, your other kidney markers, and your trend over time.
Do I need a eGFR test?
You may want an eGFR result if you are screening for kidney disease risk or you have a condition that commonly affects the kidneys, such as diabetes or high blood pressure. eGFR is also commonly checked when you are starting or adjusting medications that are cleared by the kidneys.
Testing can be especially helpful if you have signs that could fit kidney dysfunction, even though early kidney disease often has no symptoms. When symptoms do show up, they can include fatigue, swelling in the legs or around the eyes, nausea, reduced appetite, itching, muscle cramps, shortness of breath, or changes in urination.
If you have a prior abnormal creatinine, protein in the urine, recurrent kidney infections, kidney stones, or a family history of kidney disease, eGFR helps clarify whether your kidneys are filtering at an expected level for you.
Your result is best used to support clinician-directed care and follow-up testing, not to self-diagnose a kidney condition from a single number.
eGFR is a calculated estimate (not a directly measured analyte) and should be interpreted alongside creatinine, urine testing, and your clinical context.
Lab testing
Ready to order labs that include eGFR and track your kidney function over time?
Schedule online, results typically within about a week
Clear reporting and optional clinician context
HSA/FSA eligible where applicable
Get this test with Vitals Vault
With Vitals Vault, you can order labs that include eGFR and complete your blood draw at a nearby Quest location. You get a clear report that helps you understand what your eGFR means and what to look at next.
Because eGFR is calculated from creatinine, it is most useful when you can compare it with related kidney and metabolic markers on the same draw. That makes it easier to spot patterns such as dehydration effects, medication-related changes, or a persistent decline that needs follow-up.
If you want help making sense of your numbers, PocketMD can walk you through common causes of low eGFR, what “staging” means, and which companion tests to discuss with your clinician. You can also use repeat testing to track trends after changes in blood pressure control, diabetes management, or medication adjustments.
- Order online and draw at a Quest location
- PocketMD guidance to interpret results in context
- Designed for trending results over time, not one-off guesses
Key benefits of eGFR testing
- Estimates how efficiently your kidneys filter blood using a standardized equation.
- Helps stage chronic kidney disease (CKD) and decide when closer monitoring is needed.
- Adds context to a creatinine result, which can be misleading on its own in very muscular or very small-bodied people.
- Supports safer medication decisions when drugs are cleared through the kidneys.
- Helps you track kidney function trends over time, which is often more meaningful than a single test.
- Pairs well with urine and metabolic testing to distinguish temporary changes (like dehydration) from persistent kidney impairment.
- Gives you a simple, widely used number to discuss with PocketMD or your clinician when planning next steps.
What is eGFR?
eGFR stands for estimated glomerular filtration rate. It is a calculated estimate of how much blood your kidneys filter each minute, adjusted to a standard body surface area. The higher the number, the more filtering capacity your kidneys are estimated to have.
Your kidneys filter waste products and extra fluid from your blood. When kidney function declines, certain wastes can build up, and your risk of complications increases over time. eGFR is the primary lab number used to stage chronic kidney disease (CKD), especially when it stays low for at least three months.
An eGFR above 90 mL/min/1.73m² is generally considered normal when other kidney findings are also normal. Values below 60 are a key threshold because they often indicate CKD when persistent. Very low values can signal advanced kidney disease and may prompt nephrology referral and planning for more intensive management.
Even though eGFR is widely used, it is still an estimate. It can be temporarily lower during dehydration or acute illness, and it can look “better” or “worse” than your true filtration rate in people with unusually high or low muscle mass.
How eGFR is calculated
Formula
CKD-EPI equation (Creatinine, Age, Sex)
Most labs report eGFR automatically when a serum creatinine result is available, using the CKD-EPI equation along with your age and sex. Results are typically reported in mL/min/1.73m².
Because the calculation depends on creatinine, anything that shifts creatinine without changing true filtration can shift eGFR too. Recent intense exercise, creatine supplements, large meat meals, dehydration, or changes in muscle mass can all affect the estimate.
What do my eGFR results mean?
Low eGFR
A low eGFR means your kidneys are estimated to be filtering less blood per minute than expected. If your eGFR is below 60 mL/min/1.73m² and stays there for three months or longer, it commonly meets criteria for chronic kidney disease (CKD). Many people have no symptoms until kidney function is more advanced, so a low number can be the first sign.
A single low result does not always mean permanent kidney damage. Dehydration, a recent illness, certain medications, or a temporary blockage can lower eGFR, so repeat testing and companion markers (like urine albumin) often matter as much as the first number.
In-range (often above 90)
An eGFR above 90 mL/min/1.73m² is generally considered normal, especially when your urine testing and other kidney markers are also normal. If your eGFR is between about 60 and 89, it may still be acceptable for many people, but it can also represent early CKD when paired with other findings such as albumin in the urine.
Your “best” range depends on your overall health, age, and whether you have risk factors like diabetes or hypertension. Looking at your trend over time helps you separate normal variability from a meaningful decline.
High eGFR
A higher eGFR usually suggests better estimated filtration, but very high values are not always a sign of “extra healthy” kidneys. In some settings, an unusually high eGFR can reflect low creatinine from low muscle mass, pregnancy, or other factors that reduce creatinine production.
In early diabetes, some people experience kidney “hyperfiltration,” where filtration is elevated before later decline. If your eGFR seems unexpectedly high, it is worth reviewing creatinine, urine albumin, and your clinical context rather than assuming it is automatically beneficial.
Factors that influence eGFR
eGFR is strongly influenced by anything that changes serum creatinine. Muscle mass, recent heavy exercise, creatine supplementation, and a high-meat meal can raise creatinine and lower eGFR without true kidney injury. Dehydration can concentrate creatinine and temporarily lower eGFR, while overhydration can do the opposite.
Medications can matter too. Some drugs affect kidney blood flow or creatinine handling, and others require dose adjustments when eGFR is reduced. Acute illness, urinary obstruction, kidney infections, and long-term conditions such as diabetes, hypertension, glomerulonephritis, or polycystic kidney disease can also drive persistent changes.
Frequently Asked Questions
What is a normal eGFR?
For many adults, an eGFR above 90 mL/min/1.73m² is considered normal when other kidney findings are normal. An eGFR below 60 that persists for three months or longer commonly indicates chronic kidney disease (CKD). Your clinician may interpret values between 60–89 differently depending on age, urine albumin, and other risk factors.
Is eGFR the same as creatinine?
No. Creatinine is a measured blood value, while eGFR is calculated from creatinine plus your age and sex using a standardized equation. Creatinine can be affected by muscle mass, diet, and supplements, so eGFR helps translate creatinine into an estimated filtration rate.
Can dehydration lower eGFR?
Yes. Dehydration can raise your measured creatinine and make your eGFR look lower than your usual baseline. If your result is unexpectedly low, repeating the test when you are well-hydrated and not acutely ill can help clarify whether the change is temporary.
Do I need to fast for an eGFR test?
Fasting is not required for eGFR itself because it is calculated from creatinine. However, eGFR is often reported as part of a broader panel that may include glucose or lipid testing, which can have fasting recommendations. Follow the instructions for the full panel you are ordering.
What does eGFR below 60 mean?
An eGFR below 60 mL/min/1.73m² can indicate reduced kidney function. If it stays below 60 for at least three months, it often meets criteria for CKD and may affect medication dosing and monitoring frequency. A single low result can also happen with dehydration, acute illness, or medication effects, so follow-up testing is important.
Why did my eGFR change from last time?
Small changes can happen from normal biological variation, hydration status, recent exercise, diet, or lab-to-lab differences. Larger or persistent declines are more concerning and should be reviewed with companion markers such as creatinine trend, BUN, electrolytes, and urine albumin-to-creatinine ratio (ACR). Tracking results over time is often more informative than focusing on one test.