The estimated glomerular filtration rate (eFGR) blood test is used to monitor an individual’s kidney status. It can also be used to look for early signs of kidney damage. This blood test is calculated from a creatinine test and then calculating out what the eGFR happens to be. It is often ordered as part of a comprehensive metabolic panel or a basic metabolic panel when having an annual physical examination.
Those who are known to have hypertension, diabetes, or chronic kidney conditions will have the eGFR blood test routinely ordered to monitor their health. Anyone suffering from the signs or symptoms of kidney disease will typically have their medical provider order this test. If urine is foamy, there is swelling in the body, there are problems urinating, or lower back pain then this test can help to detect early damage before it becomes problematic.
Late stage symptoms that would cause this test to be ordered include swelling or numbness in the hands and feet, itchiness, darkened skin, and muscle cramping. Some people report a loss of concentration or unusual fatigue as well.
What Do My Test Results Mean?
There are five different stages of kidney damage that occur. Depending on the eGFR results, the appropriate stage of damage can be determined so that a treatment plan can be developed. These figures do not account for biological variability, so there are some individuals who may have a higher or lower stage of kidney damage despite what their eGFR happens to indicate.
Here are the normal results to expect with every stage.
- Stage 1: Anything above 90 indicates normal kidney functioning or a minimal amount of kidney damage. Numbers closer to 90 have a greater risk of at least some damage having occurred.
- Stage 2: Results that fall between 60-89 are considered to be the result of mild kidney damage. There may be proteins, casts, or cells in the individual’s urine.
- Stage 3: Results that fall between 30-59 are an indication of moderate damage.
- Stage 4: Results that fall between 15-29 are an indication of severe damage.
- Stage 5: Anything below 15 is generally treated as an indication that kidney failure has occurred and emergency interventions may be needed.
The National Kidney Foundation suggests that medical providers consider a normal eGFR to be anything above 60. Any numbers above that suggest that only mild damage may have happened, if at all, and that simple adjustments to an individual’s treatment plan are all that is necessary in order to address the situation.
What about my inulin clearance? Inulin clearance helps to determine the real GFR instead of an estimated GFR. It is often confused with insulin, but inulin is simply introduced as a marker molecule only. Its measurement over several hours after introduction can give specific results, but is not often ordered.
Here’s What You Need to Know
The eGFR blood test is not appropriate for anyone above the age of 75. This is because as people age, their muscle mass naturally begins to decrease. This lowers the levels of creatinine that are available and makes calculating the eGFR impossible to do. Anyone with a muscle wasting disease or condition would also qualify as a non-viable candidate for this reason.
For children under the age of 18, the eGFR blood test can still produce accurate results, but the calculation formulas are a little different than they are with adults. This will be handled internally by the laboratory, but asking about this calculation if low results are discovered can help to reduce the risks of human error during the diagnostic process.
People, and especially men, who are bodybuilders are who perform strength training regularly may not have useful eGFR results. This is because their creatinine levels are elevated above what is considered a normal baseline and this makes it difficult to adjust the eGFR calculations. Even the taking of a creatine dietary supplement can alter this blood test result. Certain drugs and eating a strictly vegetarian diet also affect the results of this test.
It is possible to calculate your own eGFR if you’ve had a recent creatinine blood test. The National Kidney Foundation offers an online calculator that will calculate your results if you input your testing figures. What those results mean for your individual health profile, however, can only be interpreted by a medical provider. Use this guide to determine the possible status of your kidneys, speak with your doctor about what the test results mean, and you’ll have the information needed to meet your personal health needs.