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What is GFR calculation in Kidney Disease and How to Improve It

Medically Approved by Dr. Edward Salko

Table of Contents

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Glomerular filtration rate (GFR) provides insight into a crucial function of your kidney: filtering waste products from the blood. Kidneys contain small networks of blood vessels called glomeruli which separate wastes, excess fluids, and tiny molecules from the blood. These are then flushed out from the body through the urethra.

Using GFR calculation, your doctor will detect problems concerning kidney functions. It is a key process in assessing renal disease, whether as a standalone illness or a result of another chronic condition.

Continue reading to learn more about how GFR is calculated, what the results tell you, and how to improve your score.  

What Is the Glomerular Filtration Rate (GFR) Calculation? 

Simply put, a glomerular filtration rate (GFR) calculation measures the amount of blood passing through the kidney filters or glomeruli in a minute. It is the principle behind a GFR test, which is typically taken to detect kidney disease at its early stage. 

A GFR calculator follows a formula that requires information such as your serum creatinine test result along with your personal data (age and gender) to measure the rate of filtration. In some equations, other related data are used instead. While this seems straightforward upfront, understanding your GFR needs further analysis. That’s why, for the sake of accuracy, it’s best to hand the task to the specialists.

On top of that, GFR calculation is not exactly precise, considering the intricacy of glomerular filtration. In fact, what healthcare providers derive is the estimated glomerular filtration rate (eGFR). Plus, GFR calculators may vary along with eGFR equations. 

Did You Know? As eGFR may not be completely accurate, other kidney function tests are necessary. Also, being aware of any symptoms associated with kidney problems is helpful. For example, your nails may look different with kidney disease. In addition, you may observe discoloration or detachment of the plate.

What is a normal glomerular filtration rate?

The normal range of GFR is 60 or higher. When it’s lower than 60, it could signal kidney disease, while 15 below indicates kidney failure. 

However, it’s important to note that eGFR calculation may vary among healthcare providers based on which equation they use. Nonetheless, if you have undergone an eGFR blood work, leave the interpretation to your doctor to better understand your kidneys’ condition.  

How to Improve Your GFR 

Keeping a normal eGFR means maintaining healthy kidney functions. However, in the case where your GFR score entails renal problems, you can still improve your rate of filtration following an adjustment in your diet, mobility, hydration, and other means of healthy living. 

Likewise, if your GFR score causes nothing to worry about, continue to follow through with these tips to protect your kidneys’ health. 

  1. Make your diet more kidney-friendly
young couple cutting fruits and vegetables in kitchen

When it comes to good health, some foods are far more superior than others. This remains true for renal diets, where you must avoid certain foods while favoring ones that enhance kidney filtration. 

Some of the foods that help your kidneys maintain good health and function include cranberries, blueberries, fatty fish, cabbage, olive oil, garlic, red bell peppers, red grapes, and egg whites. 

On the other hand, stir clear from foods high in sodium, sugar, and bad cholesterol. These include highly processed meats, premade meals, and canned goods. 

Aside from the fact that these food molecules make it difficult for the glomeruli to filter wastes, they also contribute to conditions that lead to abnormal eGFR scores, like type 2 diabetes and hypertension or high blood pressure

  1. Be mindful of your water intake
photo young african woman in casualwear drinking water from glass

A study published in Medicine showed a positive correlation between water volume intake and eGFR. Its clinical data also indicates a decreased albumin and creatinine, suggesting that sufficient hydration improves renal functions. 

That said if you aim to improve your GFR calculation score, make sure to keep track of your daily water intake. Although the suggested amount of water consumed daily is typically six to eight ounces glasses, your need may vary. 

For best results, consult a doctor for a tailor-fitted meal and hydration plan. 

Did You Know? Keeping your kidneys healthy is just one of the many benefits of drinking water regularly. It also improves your digestion and metabolism, as well as helps prevent arthritis. 

  1. Maintain a healthy blood pressure
photo beautiful woman at a family doctor measures blood pressure with a tonometer

As the glomeruli consist of tiny blood vessels, blood pressure can influence their function. As a result, people with hypertension are at a higher risk of developing kidney problems as the increased blood pressure causes substantial damage to the glomeruli. 

With that in mind, keep your blood pressure healthy, less than 120/80 mmHg. Do this by eliminating bad cholesterol or low-density lipids (LDL) from your diet, getting more physically active, quitting smoking the right way, and limiting your alcohol intake. 

Your lipid (fats) serum levels tell plenty about your health. So if you’re thinking of getting a lipid panel blood test to understand your cholesterol levels, it’s best to know what your lipid profile test results mean. But for an accurate reading, always refer to your doctor. 

  1. Consult your doctor about your risk for metabolic and cardiovascular diseases
photo caring caucasian female doctor use phonendoscope examine male patient heart rate at consultation in hospital

People with type 2 diabetes have a higher risk of developing slow GFR due to the amount of glucose in the blood. This is why it’s imperative to understand your risk for developing such a metabolic condition based on your family history and lifestyle. 

Those diagnosed with prediabetes are often recommended not just to cut back on their sugar intake but also to be conscious about their kidneys’ health. 

On the other hand, people with an inclination toward cardiovascular disease (CVD) also opt to check their eGFR calculation. A study in the Journal of the American Heart Association shows that the decline in eGFR links to a higher risk for heart disease.   

Tip: It’s easy to think that CVD only affects people of old age. However, even young individuals are not safe when it comes to heart conditions. Therefore, it can be highly beneficial to get tested for heart disease in your 20s

  1. Get sufficient vitamin D
photo portrait of an attractive woman with juice and phone

Vitamin D deficiency has a close association with decreased eGFR. After all, the kidneys convert vitamin D to a more viable molecule the body can use. And as a slow glomerular filtration rate entails kidney impairment, it’s no surprise that both conditions are related. 

In cases where you don’t have enough vitamin D absorption, your kidney may experience renal hyperfiltration, where your eGFR is increased. While we often paint low eGFR calculation as the more alarming end of the test, an offshoot in eGFR causes a set of risks on its own. For example, renal hyperfiltration increases your risk for cardiovascular disease

On top of abnormal GFR calculation, vitamin D deficiency has other consequences. Meanwhile, sufficient vitamin D also has several health benefits. So it’s imperative to ensure its absorption by getting enough sunlight or taking supplements if necessary.

Not sure if you have vitamin D deficiency? There are symptoms that can tell you. For an accurate test, check with a healthcare provider online.   

  1. Do regular aerobic exercise
Woman doing lunge stretch while on reformer bed

Aerobic exercise keeps your blood pumping at an optimal health for your heart. Not only does it keep your blood vessels clear of cholesterol and improve your blood pressure, but it also has favorable effects on the GFR of your kidneys

Include aerobic exercises, like walking or jogging, in your weekly routine. You can also go for high-intensity cardiovascular activities like swimming or rowing. However, it’s best to get your doctor’s recommendation and approval. 

If you’re not into intense exercises or have been limited by time, start with light physical activities you can do at home. Then work your way to increasing intensity over time. 

Frequently Asked Questions 

Does fasting affect GFR results?

It’s unclear if fasting has a direct impact on GFR results. While research shows high hydration among fasting adults decreased GFR, no evidence has been noted on the overall effect of food abstinence. 

What can make eGFR inaccurate?

Since eGFR is merely an estimate, it can be prone to inaccuracies. Hence, in assessing kidney function, it’s less likely that your doctor won’t recommend other tests. However, in most cases, if serum creatinine is not measured accurately, it can also lead to errors in eGFR calculation. 

What affects GFR the most?

Many factors go into abnormal GFR scores, such as metabolic diseases, obesity, hypertension, and blood urea nitrogen (bun) level. However, in all of this, lifestyle and diet seem to contribute the most to low GFR as they directly impact the precursor conditions.

Bottom Line

A better understanding of what GFR calculation tells you allows for more consciousness regarding your kidney health. But for accurate details on how well your kidneys function, consult with your doctor to know which other tests to take. Follow the tips above to keep your eGFR within the normal range.

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