Are your kidneys healthy? Let's learn about Kidney Function Tests in a simple way!

Have you ever wondered if our kidneys are like a filter? Yes, it's true. These two kidneys do a great job of removing waste from our body and keeping our body healthy. So, today we are going to talk about the tests that are done to find out if these kidneys are working properly. We call these kidney function tests, or in English `(Kidney Function Tests)`. Sometimes these are also called `(Renal Function Tests)`. Don't worry, this is very simple. Let's see what these are.

What are kidneys? What is their role in our body?

Simply put, the kidneys are part of our urinary system. Most people have two kidneys. They are located behind our abdomen, on either side of our spine, just below our rib cage. They are shaped like two bean pods.

The work these two little organs do is amazing. Just think:

• Filtration of waste products: It helps to filter out the unwanted substances and waste products in our blood and expel them from the body as urine. This filtration function is mainly done by tiny filters called `(Glomeruli)` in the kidneys.
• Fluid and salt balance in the body: The kidneys help maintain the proper amount of water in our body, as well as essential salts (electrolytes) like sodium and potassium.
• Hormone production:
• It produces hormones that control our blood pressure.
• The kidneys produce a hormone called ``Erythropoietin'', which helps in the production of red blood cells. Red blood cells are what carry oxygen throughout the body.
• The kidneys also contribute to the activation of vitamin D, which helps keep bones and muscles healthy.

You see, despite being small, the kidneys do a great job!

Why do we have to do a Kidney Function Test?

There are some diseases, for example, diabetes or high blood pressure, which can affect the functioning of our kidneys. If you have such a condition, your doctor may recommend these kidney tests to monitor the health of your kidneys.

Also, if you have symptoms that suggest a kidney problem, you may also be asked to have these tests. What are these symptoms?

• Blood in the urine (Hematuria)
• Foamy urine (this may indicate proteinuria)
• Pain or burning sensation when urinating (Dysuria)
• Frequent need to urinate
• Oliguria (excreting less urine than expected)
• Feeling discomfort when starting to urinate
• Swelling of the body, especially the hands, feet, and ankles (Edema)
• Feeling very tired (Fatigue)
• Nausea and vomiting
• Appetite

If you have one or more of these symptoms, it is best to seek medical advice.

What are these types of kidney function tests?

Your doctor may recommend one or more tests. These can be divided into two main categories: blood tests and urine tests.

Blood Tests

These are some of the most commonly performed blood tests:

• Blood Urea Nitrogen (BUN): This measures the amount of nitrogen in your blood. This nitrogen is produced when the protein we eat is digested and broken down.
• Estimated GFR (eGFR): This is a very important test. It measures how efficiently your kidneys filter your blood (`(Filtration Rate)`), taking into account factors such as the protein levels in your blood, age, gender (`(Sex)`), height, and weight.
• Serum Creatinine: This measures the amount of a waste product called ``Creatinine'' in your blood. This waste product called ``Creatinine'' is produced when our muscle tissue breaks down.

Urine Tests

The doctor may also ask you to test a urine sample collected over 24 hours.

• Microalbuminuria: This specifically looks for a type of protein called `(Albumin)` in your urine. Healthy kidneys produce very little of this `(Albumin)` protein in the urine.
• Urinalysis: This is a general urine test. It checks your urine for things like blood, protein, urine acidity, specific gravity, and the presence of small, tubular particles (casts) and crystals.

How do we prepare for these tests?

The way you need to prepare will vary depending on the type of test you are being asked to take.

If you are having a blood test, think about these things:

• Some blood tests may require you to fast for several hours. Your doctor will inform you about this in advance.
• Keep the skin on your hands moist so that the phlebotomist can easily insert the needle.
• If you have a fear of needles (`(Trypanophobia)`), tell your doctor or the person who is drawing your blood beforehand. They will then give you instructions on how to stay relaxed during the procedure.

If you are having a urine test, you usually don't need much preparation.

• Drink just one extra glass of water before the test. This will make it easier to provide a sufficient urine sample for the test.
• If you are menstruating, it is a good idea to tell your doctor about this as well, as menstrual blood and vaginal discharge can affect the results.

What happens during the test?

This is also a very simple process.

How to do a urine test? (Especially 24-hour urine collection)

If you have a 24-hour urine collection test, you can do it at home. Your doctor will give you a special container to collect your urine.

1. On the day of the test, first thing in the morning when you wake up, urinate into the toilet as usual. Do not collect the urine.

2. Then throughout the day, each time you urinate, add urine to the bottle provided.

3. The next morning, collect the urine that you pass into the same bottle.

4. Then take the urine sample to the doctor's office or to the lab.

A typical urine test involves simply adding some urine to a small cup provided by the lab.

How to do a blood test?

To get a blood test, you have to go to a doctor's office or a lab. There, a trained phlebotomist (a phlebotomist) uses a small needle to draw a small amount of blood, usually from a vein in your arm. This takes a few minutes. You may feel a small prick, but it is not very painful.

For some people, donating blood can be a bit uncomfortable. That's normal. But these tests are very important to know about the health of your kidneys. Doctors know this, so they will help you do this as easily as possible.

What can you expect after the test?

Kidney function tests are not simple and do not carry any long-term risks. However, some people may experience the following after donating blood:

• The needle may sting a little where it was inserted.
• You may feel a little dizzy.
• Some people may feel a little tired.

If these symptoms persist, or if you notice anything else unusual , it's a good idea to talk to a doctor.

What do these test results say?

This is the most important part. These test results are what tell you if your kidneys are working as expected. Most kidney tests focus on two main measurements: `eGFR` (Estimated Glomerular Filtration Rate) and `uACR` (Urine Albumin-Creatinine Ratio).

What is eGFR (Estimated Glomerular Filtration Rate)?

`eGFR` measures how much blood your kidneys filter per minute (in milliliters).

• It is good if the average `eGFR` value for an adult is 100 or higher .
• If the `eGFR` value is between 60 and 100 , it means that there may be some damage to the kidneys, but the kidneys are still functioning well.
• An eGFR value of less than 60 may indicate the presence of chronic kidney disease (CKD).

How does the `eGFR` value change with age?

As we age, our eGFR naturally decreases slightly. This can happen even if you don't have chronic kidney disease. Here are the typical eGFR values ​​for different age groups:

• Age 20-29: Average eGFR value 116
• Age 30-39: Average eGFR value 107
• Age 40-49: Average eGFR value 99
• Age 50-59: Average eGFR value 93
• Age 60-69: Average eGFR value 85
• Age 70+: Average eGFR value 75

These are just average values. Talk to your doctor to find out exactly what your eGFR is.

What is uACR (Urine Albumin-Creatinine Ratio)?

`uACR` measures the amount of `(Albumin)` (a type of protein) and `(Creatinine)` (a waste product) in your urine. It is the ratio of these two that is looked at (in milligrams per gram - mg/g).

• A normal `uACR` value should be less than 30 mg/g.

How high is the uACR value, the higher the risk of kidney failure?

If the `uACR` value is 300 mg/g or higher, it means that you have a very high risk of kidney failure. Also, the risk of having a heart attack `(Myocardial Infarction)` or a stroke `(Stroke)` is also high.

How long does it take to know the results?

This can vary from place to place. Sometimes the doctor will talk to you about the results the same day. Or, the sample may be sent to a lab and the results may take a few days.

What if the results show the early signs of kidney disease?

Don't worry. If your kidney test results show early signs of kidney disease, your doctor will talk to you about what to do next and your treatment options. You may be given antihypertensives to control your high blood pressure. You may also be referred to a doctor who specializes in kidney disease (a nephrologist).

If your results are not as expected or are abnormal, your doctor may recommend more frequent kidney tests in the future to monitor your health and any underlying conditions.

When should you see a doctor?

If you have chronic kidney disease (CKD), or are at risk of developing CKD, see a doctor immediately if you experience any of these symptoms:

• Passing urine more than usual
• Blood in the urine
• Foamy urine
• Feeling very tired
• Muscle pain or aches
• Nausea or vomiting
• Difficulty breathing (Dyspnea)
• Swelling, especially in the hands, feet, or ankles

Can drinking water lower creatinine? - Is this true?

This is a question that many people ask. If you drink a lot of water before a kidney blood test, your creatinine levels may appear to be slightly lower for a short time. However, it is important to remember that this will only temporarily affect the test results . Drinking a lot of water will not reverse the damage that has already been done to your kidneys, nor will it have a long-term positive effect on your creatinine levels.

If you have early-stage chronic kidney disease (CKD), it's best to work with a nephrologist and a renal dietitian to develop a kidney-friendly diet.

Finally, a few things to keep in mind (Take-Home Message)

Kidney function tests can be a bit uncomfortable and intimidating, but they are very important tools that help doctors check the health of your kidneys and diagnose conditions that affect them.

Although it feels like a small needle prick during a blood test, the entire process only takes a few minutes. A urine test is a painless test that you can easily do at home. If you are uncomfortable giving your urine sample to your doctor, you can avoid the inconvenience by putting it in a bag and giving it to them.

Remember, if you have any questions or concerns, never hesitate to talk to your doctor. They are there to help you. These tests will help keep your kidneys healthy!

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