Let's learn about Kidney Function Tests in simple terms.

Your doctor may have asked you to have a blood test or a urine test to check your kidney function, right? Sometimes we feel a little scared and nervous when we are asked to do such a test. Some people are afraid of having blood drawn from a needle, and some may feel a little strange about giving someone a cup of urine. But these feelings are very normal. The important thing is that these tests are a very important tool to know if your kidneys are healthy and working well.

First, let's see what these kidneys are? Why are they so important to us?

Simply put, our kidneys are like an amazing filter system in the body. Most people have two kidneys. They are located behind the abdomen, on either side of the spine, just below the rib cage.

The main function of the kidneys is to purify our blood. That is, to filter out unwanted waste products and excess water from the blood and excrete them from the body as urine.

Not only that, the kidneys perform several other very important functions:

• Produces hormones that control blood pressure .
• It produces a hormone called erythropoietin . This is what helps make red blood cells. Red blood cells are what carry oxygen throughout our bodies.
• Activates vitamin D, which is essential for keeping bones and muscles healthy.

Why do you need a kidney test?

Your doctor may have several reasons for performing a kidney function test.

The main reason is that you have medical conditions like diabetes or high blood pressure . These diseases can damage the kidneys over time. So, these tests help to regularly monitor whether the kidneys of a person with such a medical condition are functioning well.

Additionally, if you have symptoms that suggest a kidney problem, your doctor may recommend this test.

What are the types of tests done on the kidneys?

There are two main types of tests to check kidney function: blood tests and urine tests.

Blood Tests

• Serum Creatinine: Creatinine is a waste product produced when our muscles work. Healthy kidneys filter this creatinine from the blood and excrete it in the urine. When the kidneys function poorly, the level of creatinine in the blood increases. So this test measures how much creatinine is in the blood.
• Blood Urea Nitrogen (BUN): When we eat protein-rich foods, a nitrogenous waste product is formed during their digestion. It is called urea. This urea is also filtered and removed by the kidneys. If the kidneys are not functioning properly, the urea level in the blood increases.
• Estimated GFR (eGFR): This is often the main measurement of kidney function. GFR stands for Glomerular Filtration Rate. That is, how much blood your kidneys filter per minute. Because this is difficult to measure directly, it is calculated using factors such as your blood creatinine level, age, and gender. That is called eGFR.

Urine Tests

• Urinalysis: This is a general urine test. Your urine sample is checked for things like blood, protein, and sugar. It also checks for things like the acidity of your urine.
• Microalbuminuria: This is a special urine test. It looks for very small amounts of a special protein called albumin in the urine. This protein is not filtered by healthy kidneys. The presence of albumin in the urine can be an early sign that the kidneys are starting to be damaged.
• 24-Hour Urine Collection Test: Sometimes your doctor may ask you to collect all the urine you pass throughout the day and test it. This can help you see exactly how much waste your kidneys are removing each day.

How do you prepare for these tests?

The way you prepare may vary slightly depending on the test you are taking.

For a blood test:

• You may be asked to fast for a few hours before the test. Your doctor or lab will advise you on this.
• If the skin on your hands is dry, it's a good idea to apply moisturizer the day before the test. This will make it easier for the person taking the blood to find a vein.
• If you are afraid of needles, tell the person taking your blood beforehand. They will help calm you down.

For a urine test:

• Usually, no special preparation is required for a urine test. However, it is a good idea to drink a glass of water before the test. This will make it easier to provide the required amount of urine sample.
• If you are a woman and are taking the test on a day when you are menstruating, tell your doctor or lab about it, as menstrual blood can affect the results of the report.

After the test... how do you understand the report?

When you get your test report, don't be alarmed by the numbers on it. Your doctor is the best person to explain what they mean to you. But in general, there are two main things to look for.

1. Estimated Glomerular Filtration Rate (eGFR)

This is the filtration rate of the kidneys. A healthy adult has an eGFR of 100 or more.

• An eGFR value between 60 and 100: This means that the kidneys have suffered some damage, but they are still functioning well.
• eGFR value below 60: This may indicate the presence of Chronic Kidney Disease (CKD).

2. Urine Albumin-Creatinine Ratio (uACR)

This measures how much albumin (a type of protein) is in your urine.

• Normal value: less than 30 mg/g.
• Risk value: A value of 300 mg/g or higher indicates a high risk of kidney failure.

What if the results of the report show an early case of kidney disease?

First of all, don't panic. If your report results indicate early stage kidney disease, your doctor will explain the next steps to take.

• You may be prescribed medication to control your blood pressure.
• You may be referred to a doctor who specializes in kidney diseases, or a nephrologist .
• You may be asked to have regular tests to monitor the condition of your kidneys.
• You may also be advised to make dietary changes.

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