eGFR

What is eGFR?

The estimated glomerular filtration rate (eGFR) measures how well your kidneys are functioning. It measures your kidneys’ ability to filter waste and toxic components from the blood, determining if you have kidney disease, and if so, how severe it is.

Previously, a measured glomerular filtration rate (GFR) was the gold standard for determining kidney function^[1]. However, it is not always practical to measure and so an eGFR is used instead.

An eGFR is calculated based on serum creatinine levels. Creatinine is a waste product of protein digestion and muscle tissue breakdown. It is filtered out of the blood by the kidneys and excreted via urine at a constant rate. So, if kidney function declines, less is removed from the blood, so serum concentrations increase. Using creatinine to estimate the glomerular filtration rate is a practical and accurate measure of kidney function^[2].

What are Normal eGFR Levels?

Normal eGFR levels can vary depending on the testing laboratory. A healthy eGFR range for our tests is 60 – 500 nmol/L for men and women.

What Causes eGFR to Change?

Because eGFR measures how well your kidneys are functioning, changes in eGFR levels may indicate an issue with the kidneys.

Causes

Several factors can cause eGFR levels to change, such as:

Acute Kidney Injury

• Dehydration

  can cause a temporary drop in eGFR until corrected

• Severe infections

  like sepsis can cause deterioration in kidney function

• Medications

  non-steroidal anti-inflammatories (NSAIDs), like ibuprofen, and antibiotics used to treat bacterial infections can interrupt kidney function

• Kidney stones or tumours

  Obstructions that block the urinary tract can affect kidney function

The most common cause of eGFR changes is chronic kidney disease which can be caused by:

• High blood pressure (hypertension)

  Damages kidney blood vessels causing a decline in kidney function

• Glomerulonephritis

  Inflammation of the specific kidney components responsible for filtering the blood

• Diabetes

  High blood sugar levels can cause damage to the kidneys if they are exposed to them over a long period

• Polycystic kidney disease

  An inherited condition that causes cysts to form on the kidneys^[3]

• Enlarged prostate

  An enlarged prostate in men can affect kidney function^[4]

Symptoms

In the early stages of kidney disease, many people do not experience any symptoms of kidney disease.

The most common symptoms of advanced chronic kidney disease are:

• Tiredness

• Shortness of breath

• Swollen ankles, feet, or hands

• Feeling sick

• Blood in your urine

• Erectile dysfunction in men

• Sleep issues and insomnia

• Weight loss

• Loss of appetite

• Muscle cramps

• Headaches^[5]

How to manage eGFR levels

You may be able to improve your eGFR number by making some simple lifestyle changes, depending on the underlying cause. For example, people who have chronic kidney disease may not be able to improve their eGFR, but making the changes will still be beneficial for their overall health.

If an acute kidney injury is causing lower than normal eGFR levels, it’s likely your results will rise once the injury has been treated.

Some of the things you can do include:

• Take part in regular exercise

• Eat a healthy, balanced diet

• Give up smoking

• Limit your alcohol intake

• Drink small sips of water continuously throughout the day

What is an eGFR Blood Test?

An eGFR test assesses your kidney function by measuring the amount of creatinine in your blood. When you consume protein or when your muscles are naturally broken down, creatinine is released as a waste product and your kidneys filter it out of the blood and into the urine. If your kidney function declines, more creatinine will be in circulation and may signify a problem with your kidneys.

An eGFR test requires a blood sample either from a vein in your arm or using a finger prick blood test. Your blood sample can then be analysed to quantify the creatinine level in your blood.

The test can help to identify kidney problems and can be used to monitor kidney health if you are obese or have:

• Heart disease

• Diabetes

• A family history of kidney disease

• High blood pressure

• A history of smoking

How Does it Work?

You can test your eGFR at home with the following at-home test kits from Forth:

• Kidney Function Blood Test
• Liver Function Blood Test
• Advanced Health Check
• Ultimate Health Check

To find out how well your kidneys are working, you’ll need to:

• Choose your test kit and we’ll post everything you need to you

• Take your sample according to the instructions in the box

• Post your sample to our lab for analysis using the prepaid envelope in your kit

• One of our doctors will review your results

• You can review the doctor’s comments on your secure health dashboard

Tips for Protecting Your Kidneys

It isn’t always possible to prevent chronic kidney disease, but there are steps you can take to reduce your risk and keep your kidneys healthy.

Stay hydrated

Drinking an adequate amount of fluid daily is paramount for kidney health. Dehydration produces urine which has a higher concentration of waste products. The more concentrated the urine, the more likely you will be to develop crystals which can reduce kidney function and lead to the development of kidney stones^[6].

Get regular exercise

Physical activity is good for all aspects of health but it can help to support the overall function of your kidneys because it reduces the risk of developing conditions such as high blood pressure, which may cause chronic kidney disease.

Research shows that exercise is also beneficial for people who have already been diagnosed with kidney disease. Aerobic or resistance training or a combination of the two can improve glomerular filtration and reduce cardiovascular risk factors in kidney disease patients^[7].

Eat a healthy diet

Consuming a diet that is healthy and balanced will help your kidneys because it will reduce the risk of developing high cholesterol and high blood pressure, risk factors for kidney disease.

You should look to incorporate lots of fruit, vegetables, and whole grains into your daily diet, choosing healthy protein options to accompany them, like plant-based protein and lean cuts of meat or fish.

Reduce your alcohol intake

Alcohol can have a damaging effect on many of the body’s organs and systems, including the kidneys. Alcohol can disrupt the hormones that control kidney function and impair the regulation of sodium and fluid which can contribute to kidney failure^[8].

In the UK, it is recommended that adults should drink less than 14 units of alcohol per week. Ideally, this should be spread out across at least three days. There is no “safe” level of drinking, but sticking within these guidelines can help to reduce health risks^[9].

Written by Leanne Edermaniger

Based in the UK, Leanne specialises in writing about health, medicine, nutrition, and fitness.

She has over 5 years of experience in writing about health and lifestyle and has a BSc (hons) Biomedical Science and an MSc Science, Communication and Society.