Kidney Function Test – Purpose, Types & Risks

As you are probably aware, the human body consists of two kidneys, which play a vital part in filtering waste materials from the blood and expelling them through urine. Thus, if doctors suspect any kidney disease in your body, they might prescribe a kidney function test to determine if you have medical conditions related to your kidneys.

Are you facing kidney diseases and trying to find out more about a kidney function test? Then, read till the end of this article to find out all about it!

A doctor might ask you to take a kidney function test if you suffer from symptoms like blood in the urine, frequent urination urges, painful urination and high blood pressure. Such a test is conducted by examining your blood or urine samples to evaluate if your kidneys are working correctly and completing their normal functions. Usually, they conduct these tests for measuring Glomerular Filtration Rate (GFR), which determines if your kidneys are efficiently removing wastes from your system.

If you are curious to know the cost of kidney function tests in India, it differs from one lab to another. But, in general, the price ranges between ₹ 400 and ₹ 1,100. Thus, if you are curious about what a kidney function test is, it helps evaluate the performance of your kidneys.

Now, you must be wondering “which test is done for kidney function?”. Healthcare settings generally use the following types of kidney function tests.

1. Urinalysis

The most common kidney function test includes urinalysis. Doctors use it for testing protein and blood in your urine. While there can be various reasons for protein in the urine, not all are related to diseases. For example, infection and extreme heavy workouts often increase protein in the urine. Therefore, the doctors will ask you to provide a 24-hour urine sample. With this, they determine how fast your kidneys can clear creatinine, a waste product, from your body.

2. Serum Creatinine Test

It is a blood test used for testing kidney functions. It helps to examine if creatinine is building up in your blood. The doctors draw your blood sample and send it for testing in a lab. If the creatinine level is high in your blood, it means the kidneys are not doing their function of filtering it out. As per National Kidney Foundation (NKF), creatinine levels higher than 1.2 milligrams/decilitre for women and 1.4 milligrams/decilitre for men represent kidney disorders. Therefore, this can be considered a normal range for kidney function tests.

3. Estimated GFR

Doctors often use this test for kidney function to examine the capability of your kidneys to filter wastes. It uses factors such as age, race, gender, height, and creatinine levels to check the kidneys' efficiency. If your doctor finds your result lower than 60 millilitres/minute/1.73m2, they might design a treatment procedure, as it would mean a severe kidney disorder in your system.

4. Blood Urea Nitrogen (BUN)

Just like the previous ones, a BUN test is also responsible for checking waste products in your blood. In addition, doctors usually rely on this test for measuring urea nitrogen in your blood, which is a breakdown product of protein. Apart from kidney diseases, even common medications like aspirin and antibiotics can increase your BUN. The average BUN level is about 7-20 mg/dl, but anything higher means a problem for your body.

While anyone can get kidney disease, people aged 65 years or older are most at risk of getting these diseases. Moreover, women are at higher risk of kidney problems than men. Apart from that, the following risk factors might contribute to getting kidney diseases for individuals.

• Diabetes and high blood pressure 
• Family members with kidney diseases 
• African-American, Hispanic, Native American, or Asian races 
• Obesity and weight issues 
• Excessive smoking and drinking 
• A history of acute kidney injury (AKI)

Now that you know the normal values of kidney function tests, you must be curious to know when to take such a test. The following symptoms represent problems with your kidneys. If you find such symptoms in your system, you should consider taking a kidney function test.

• Lack of energy and weakness 
• Trouble sleeping 
• Dry and itchy skin 
• Lack of appetite 
• Urge to urinate more often 
• Blood in urine 
• Persistent puffiness under the eyes
• Swollen feet and ankles 
• Cramping muscles

Now, the question is how to test kidney function? Commonly, doctors use either urine or blood samples.

1. 24-hour urine sample

Doctors use this sample to examine the amount of creatinine your body expels in a day. If your doctor asks for this sample, you need to urinate in a container provided by them for the entire day. Then, send the container to your doctor or the laboratory for testing the next day.

2. Blood sample

Tests like BUN and creatinine kidney function tests are done from the healthcare setting. A technician will draw blood from your veins by tying an elastic band and then cleaning the area. They will store the blood in a test tube and send it to a lab.

If your doctors find kidney problems in your body after conducting a renal kidney function test, various types of treatments can be used.

1. Medication

If doctors diagnose your kidney problems in the early stages, they suggest medications after finding out the exact causes of the problem. For instance, medicines such as ramipril, enalapril, and lisinopril are given for treating high blood pressure. On the other hand, doctors may prescribe atorvastatin and simvastatin if you have high cholesterol. Moreover, doctors also provide medicines for anaemia, water retention, and bone problems, contributing to kidney disorders.

2. Dialysis

Kidneys often stop working for people suffering from chronic kidney disorders. In such conditions, doctors prefer dialysis to handle the situation. The process includes removing waste products and excess fluid from the blood. Haemodialysis involves using an external machine for diverting blood and filtering it. The clean blood then returns to the body.

On the other hand, in Peritoneal dialysis, a fluid is pumped into a specific space inside your stomach. It helps draw out waste products from your blood while passing through the vessels lining your tummy.

3. Kidney Transplant

It is an alternative for dialysis in case of severely reduced kidney functions. It involves a significant surgery for replacing your kidney with a healthy one. You will also have to take medicines such as immunosuppressants for the rest of your life. If you do not find a donor for a healthy kidney, you can also live with one kidney by getting rid of the affected one. You might have to continue dialysis while waiting for a transplant. Survival rates for kidney transplants are impressive.

You can try to prevent kidney problems by following the below-mentioned precautions.

• Manage your blood sugar by reducing diabetes issues.
• Take medicines to reduce blood pressure.
• Maintain a healthy weight and avoid obesity.
• Consume a healthy food diet, including fruits and vegetables.
• Reduce smoking and drinking addictions.
• Restrict over-the-counter pain medication consumption.

Therefore, conducting a kidney function test is essential to diagnose any kidney-related diseases quickly and start treatment. As you probably know already, the kidney is a vital organ, and your health can deteriorate if it stops functioning. The type of test and treatment depends upon the severity of symptoms in your body.