What is the Most Accurate Test for Kidney Function?

Because your health matters.

Kidney function is assessed using several tests that measure how well your kidneys filter waste from the blood. These tests can detect early kidney damage, monitor existing disease and help build an accurate picture of your overall kidney health.

As the kidneys also regulate blood pressure, support red blood cell production and activate vitamin D, reduced kidney function can have wide-reaching effects. Testing your kidney function can highlight problems early, when treatment and lifestyle changes can make the most difference.

Our private Kidney Function Test offers a quick, accurate way to understand how your kidneys are working. It’s included in our full body health check packages.

Explore our packages and book online today.

How it works

1. Select and book your package

View our health test packages and book a full body private health check. All our individual tests can be added to any of our private health check packages. Just call our team on 0800 652 2183 before your appointment to add an extra test.

2. Make an appointment

Choose the venue, date and time that suits you. With over 2000 appointments available nationwide every week, you're sure to find a convenient time, date and venue.

3. Attend your appointment

A trained health assessment specialist will carry out your assessment. The whole process only takes around 20-30 minutes.

4. Fast, accurate results

Your results will be available 24/7 through our online dashboard, My Wellness. You will receive an email notification as soon as your results are ready for viewing. Processing times vary by test, with some results accessible on the dashboard in as little as three days. The online dashboard also provides easy access to a downloadable PDF, making it simple to share your results with your GP.

What is a Kidney Function Test?

The Kidney Function Test includes several tests which, when combined, give an overview of the health of your kidneys. Together, these tests can check for signs of kidney disease and other health issues, as well as measure how well your kidneys are working.

Tests include analysing blood samples and, in some instances, urine to assess whether or not the kidneys are functioning as they should. Markers such as serum creatinine levels are measured to determine the amount of waste products found in the blood. Normally, creatinine and other waste products would be filtered out of the bloodstream by the kidneys. However, if the kidneys are not working properly, effective blood filtration is not carried out.

The kidneys are part of the urinary system and help to filter waste materials from the body, excreting them as urine. Furthermore, the kidneys are also responsible for producing:

• Hormones that regulate blood pressure and regulate red blood cell production.

• Substances which activate Vitamin D, for strong bones and muscles.

Therefore, should there be any dysfunction of the kidneys, this can lead to further health problems. A Kidney Function Test can detect irregularities in kidney function and identify the presence of kidney disease. Once problems have been flagged, the appropriate course of action can be taken. Testing the function of your kidneys with a Kidney Function Test is therefore important to help limit disease progression and make a start on treatment.

How is kidney function measured?

Kidney function tests look for markers that signal how well the kidneys are filtering waste. In a healthy system, waste products are removed from the blood and passed out in urine. When the kidneys aren’t working properly, these waste levels stay higher in the bloodstream because filtration is reduced.

Urine tests add another layer of information. Finding bacteria, blood cells or protein in a urine sample can point to infections, kidney stones or other issues, helping to show whether the kidneys need further investigation.

How can you test kidney function?

Urine tests

Kidney function can be assessed using a urine test, also known as a urinalysis or urine analysis. A small sample of your urine is taken for analysis, looking for signs of kidney disease or dysfunction.

As well as measuring kidney function, urine tests can also be used to monitor the progression of kidney disease. A urine test can also track health issues leading to kidney disease, such as diabetes. Urinary tract infections (UTI) can also be detected from a urine sample.

Health professionals will look at a variety of factors when testing your urine:

• Appearance: dark yellow or brown coloured urine can be an indicator of a problem. Also, if it appears foamy, cloudy or has a strong odour, this may be a sign of kidney dysfunction or infection.

• Under the microscope: by looking at a urine sample under a microscope, specialists can check for bacteria, or red and white blood cells. The presence of these can indicate the need for further investigation.

• Dipstick test: a stick dipped into your urine sample that changes colour when reacting to certain substances is another useful kidney function test. Dipstick tests can measure levels of blood, protein, glucose and acidity in your urine sample. Culture test: this test determines the specific type of bacteria causing a urinary tract infection.

Blood tests

Serum Creatinine Blood Test

One of the blood tests that checks kidney function is the Serum Creatinine Test. This measures the creatinine levels in your blood. Creatinine is a waste product that is usually filtered out of the blood by the kidneys.

Serum creatinine levels increase if there are any issues with kidney function. Normal creatinine levels differ depending on sex, age and also body type. For example, the amount of muscle mass you have also affects your normal creatinine levels.

eGFR Blood Test

The eGFR (estimated glomerular filtration rate) Test for kidney function is one of the main tests to check on the health of your kidneys. The test involves a blood sample being taken to calculate how well your kidneys filter out waste from the blood.

The eGFR number is based on an individual's serum creatinine level, age, and sex. Your eGFR number is calculated by the laboratory analysing the blood sample.

Your results report will help you to understand whether your eGFR number is high (normal) or low (impaired) for you as an individual.

Urea

A urea test may be performed to measure the level of urea in your blood. Urea is a waste product that is produced when the body breaks down proteins. Normally, the kidneys remove urea from the blood.

If your kidneys are not functioning properly, the level of urea in your blood may increase. Therefore, a urea test can help assess the functioning of your kidneys by measuring the urea level in your blood.

Cystatin C Test

The Cystatin C Test is another blood test to evaluate kidney function. Following an eGFR Test, a specialist may order a Cystatin C Test for various reasons. This can be used to check on any unclear past test results.

If you have a lot of muscle mass, e.g. you are a bodybuilder, this can affect your Serum Creatinine Test results. However, Cystatin C Test results are not affected by muscle mass.

Other tests

Kidney ultrasound

A kidney ultrasound, also referred to as a renal ultrasound, is a non-invasive test that produces images of your kidneys using sound waves. From this, health practitioners can detect abnormalities in the kidneys.

A kidney ultrasound can be used to identify:

• Changes to the size or shape of the kidneys

• Restricted blood flow to the kidneys

• Damage to the kidneys

• Kidney stones, cysts or tumours

Kidney biopsy

To investigate the cause of a kidney problem, a kidney biopsy may be carried out. Kidney biopsies also help to gauge the severity of a kidney problem and what would be the best course of treatment.

A kidney biopsy may be recommended if previous test results reveal:

• Blood in urine (haematuria)

• Protein in urine (proteinuria)

• Kidney disease

• Nephrotic syndrome

• Signs of glomerular or inflammatory kidney disease

A kidney biopsy can also be carried out to monitor treatment for an existing kidney problem, keep track of kidney damage, kidney tumours and other less common kidney related health conditions.

Genetic testing

A genetic test can help health professionals identify a genetic condition or increased risk of developing a genetic disorder. In a genetic test, a blood or saliva sample is taken and analysed. Specialists are trained to look for changes in your genes that could indicate a genetic predisposition towards developing kidney disease.

Genetic testing is useful in helping to detect, monitor and manage kidney diseases and other health conditions. This type of testing is particularly insightful should you have a family history of kidney disease.

What are some early warning signs of kidney disease?

Most people with kidney disease show no symptoms because the body can cope with a significant reduction in kidney function. Early warning signs, if any appear, may go undetected, and the disease left untreated. As kidney disease progresses, symptoms will start to show. However, at this point, damage to the kidneys has already taken place.

A test for kidney function may be advisable should you experience any of the following symptoms of kidney disease:

• Unexplained weight loss

• Poor appetite

• Swollen ankles, feet or hands (oedema)

• Shortness of breath

• Tiredness

• Blood in your urine

• Urinating more than usual (especially at night)

As there is no cure for chronic kidney disease, starting treatment early to manage symptoms and prevent the disease from getting worse is highly important. In stage 1 of kidney disease, the disease progression can be slowed down, and lifestyle changes can be made to limit kidney damage. Early detection of kidney disease can be achieved through undergoing regular Kidney Function Tests.

How to check your kidney function

Kidney Function Tests are included in our range of health checks, giving you peace of mind over the health and function of your kidneys. Moreover, undergoing a health MOT will assess how well other vital organs and systems work in the body.

Our full body private health checks are designed for busy people who want to take control of their health. Our tests are quick, accurate, convenient and completely stress-free. No waiting for an appointment, no invasive procedures, no embarrassing questions, no long travel times and no busy waiting rooms.

Trained health assessment specialists carry out all tests in over 350 venues across the UK and Ireland, so you get accurate professional health checks within 20 minutes of your home. Our private health checks include all the tests you need to take a proactive approach to monitoring and improving your health.

Any individual tests can be added to any full body health check. Just book one of our full body private health assessments and call us before your appointment to add an extra test.

BOOK NOW

Need help? Call free on 0800 652 2183 to speak to one of our team.