Creatinine and eGFR; What Are They and Why Are They Important?

‍Creatinine is a byproduct of the chemical compound creatine; it is found in every person's  bloodstream.  Creatinine is the waste product left over from the energy making process that your muscles need.   Healthy kidneys filter creatinine out of the blood, and it exits the body as a waste product in your urine. 

If kidneys are damaged, they cannot work as well, and do not remove as much waste products from the body.  Glomeruli are tiny filters in your kidneys.  Their job is to help remove waste products from your blood.  If damaged they are unable to perform that job as needed, leaving waste in your bloodstream.  Waste products can be measured in the blood.  Checking the creatinine level in your blood is one way to see how well your kidneys are working.  The creatinine level is used by your healthcare provider to calculate your eGFR. 

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eGFR (estimated glomerular filtration rate) gives the percentage at which your kidneys are functioning and determines your stage of kidney disease. It is calculated from a creatinine blood test and your gender, age, race, and body size. eGFR helps providers to detect kidney disease in its early stages. If detected early you may be able to slow or stop the damage to your kidneys.  The test also shows healthcare providers what stage of existing kidney disease a patient is in.  There are five stages of kidney disease. As the disease progresses, the GFR number decreases.  

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The Five Stages of Kidney Disease

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Stage 1: eGFR of 90 or above, normal kidney function.

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Stage 2: eGFR between 60 - 89, mild loss of kidney function.

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Stage 3: eGFR between 30-59, moderate kidney function.

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Stage 4: eGFR between 15-29, severe kidney damage.

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Stage 5: eGFR less than 15, kidneys close to failure or already failed

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Video

This video from the National Kidney Foundation goes into more detail between eGFR and CKD. The transcript of the video is below.

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Video Transcript

Most people have two kidneys which is about the size of their fist located in their lower back.  Just like your brain or heart, kidneys keeps you alive.

The kidney numbers and different colors create the CKD heat map which shows you the possible risk of your CKD getting worse and your risk for heart disease.

The eGFR number shows CKD stages G1 to G5. The eGFR number ranges from more than 90 to less than 15. A higher eGFR is better the uACR includes three levels:

·       A1 which is normal and less than 30

·       A2 which is moderate and is 30 to 300 and

·       A3 which is severe and is more than 300

It's better to have a lower uACR.  

·       Green means you do not have chronic kidney disease or that you are at the lowest risk for CKD getting worse.

·       Yellow means increased risk for CKD getting worse

·       Orange means high risk for CKD getting worse

·       Red means the highest risk for CKD getting worse

How well you take care of your kidneys will affect how you move along the CKD heat map.  Here's an example:

If your eGFR is 35 which is G3b on the map and if your uACR is 350 which is A3 on the map, draw a line down from A3 and another across from G3b.  They meet at a red box which means that you are at the highest risk for Chronic Kidney Disease getting worse.

The good news is that when it's found early and treated right the outlook for kidney disease patients can be very bright.

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If you are concerned that you have Chronic Kidney Disease (CKD) and have not been diagnosed, please see your physician as soon as possible.

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References

‍National Kidney Foundation

‍American Kidney Fund

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About the Author

Monica McCarthy has bachelors in Political Science and Criminal Justice from Central Washington University.  A majority of her career was spent as a political consultant.   She currently works at KidneyLuv as a staff writer.

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Patient Education Disclaimer

This material is for informational purposes only. It does not replace the advice or counsel of a doctor or health care professional. KidneyLuv makes every effort to provide information that is accurate and timely, but makes no guarantee in this regard. You should consult with, and rely only on the advice of, your physician or health care professional.

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