Fluctuations in eGFR

Estimated glomerular rate (eGFR) is a tool doctors use to find out how well your kidneys are working. A low eGFR can be a sign of kidney disease or kidney damage. But your eGFR can go up or down depending on other factors as well.¹

What is eGFR?

Estimated glomerular rate measures how well your kidneys can filter out waste and extra water from the blood. To arrive at your eGFR, your doctor will take a blood sample and calculate how much of a protein called creatinine is present in your blood.¹

Creatinine is one of the waste products that kidneys remove from the blood. Your body produces creatinine during digestion of proteins from your food. The normal breakdown of your muscles also produces creatinine.¹

Along with a blood test, your age, sex, and body type also factor into your final eGFR. A low eGFR may suggest that your kidneys are not working properly. An eGFR lower than 90 could be a sign of kidney disease. In general, as kidney disease becomes more serious, eGFR gets lower.^1,2

Factors that can lower your eGFR

One of the main reasons for a decrease in eGFR is reduced kidney function. People who have chronic kidney disease (CKD) or other kidney damage are likely to experience a decrease in eGFR. Some other things that can decrease your eGFR are:^2-4

• Smoking – Using tobacco and smoking can increase your risk for kidney disease.
• Obesity – Having an unhealthy body weight is linked to poor kidney function.
• High blood pressure – The top number of your blood pressure measurement, or the systolic blood pressure, is related to lower eGFR and kidney disease.
• Diabetes – Having high blood sugar can decrease kidney function.
• High muscle mass – Your muscles go through normal breakdown so that new muscles can be created. This process produces creatinine, which is used to measure eGFR. As a result, people with high muscle mass – like bodybuilders – might have a lower eGFR because they have more muscle mass to break down.
• Dehydration – Not drinking enough water can lower your eGFR.
• Diet – Eating a lot of meat can also increase the amount of creatinine in your blood, lowering your eGFR.
• Nonsteroidal anti-inflammatory drugs (NSAIDs) – These drugs are available over the counter and are commonly used as painkillers. But taking NSAIDs regularly or at high dosage can be harmful to the kidneys.
• Certain herbal or dietary supplements – Some supplements may include ingredients that are bad for the kidneys. Tell your doctor about any supplements you are taking.

Factors that can raise your eGFR

If you have kidney disease, then getting treatment for it and any related health conditions can help improve your eGFR. Certain prescription drugs may slow down kidney damage and decline. Making certain lifestyle changes also can help improve your eGFR, such as:²

• Not smoking – Smoking is a big risk factor for many chronic health conditions, including CKD.
• Drinking plenty of water – Avoiding dehydration may help your kidneys work better and raise your eGFR.
• Getting regular exercise – Experts recommend doing some physical activity for at least 30 minutes every day. This can help you maintain a healthy weight.
• Adopting a kidney-friendly diet – Eating a diet that contains fewer processed foods, salty foods, and high-fat foods is better for your kidneys. Also, since digesting meat produces creatinine, eating less meat can reduce the amount of creatinine your kidneys need to remove from the blood.

What do changes in eGFR mean?

Changes in your eGFR may be related to kidney function. They may suggest that your kidneys are not working as well. But there are other factors that can affect your eGFR.⁴

It is common to see changes in your eGFR when you are tested again within a few months. You might see that your eGFR is much higher or lower than the last time you were tested. This might be because of how eGFR is measured and the uncertainty related to this measurement.^2,5

It is helpful to look at the trend in your eGFR over a long period (a few years) to get a better understanding of your kidney function. Your doctor can help you understand why it might be changing over time.^2,5