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Kidney Function Test

Tests Included
Kidney Function Test

Overview of Kidney Function Test

What is Kidney Function Test?

Kidneys play an important role in the removal of waste products and maintenance of water and electrolytes balance in the body. Kidney Function Test (KFT) includes a group of blood tests to determine how well the kidneys are working.

Sample Type

The sample type collected for Kidney Function Test is: Blood

Preparation for Kidney Function Test

  • Do not eat or drink anything other than water for 8-12 hours before the test.

Why Get Tested for Kidney Function Test?

The Kidney Function Test is performed:

·         As a part of routine health checkups

·         To help diagnose disease affecting the kidneys

·         To screen people at risk for the development of kidney diseases

·         To monitor treatment efficacy of kidney diseases

Understand more about Kidney Function Test

The kidneys are a pair of bean-shaped organs located on either side of the spinal column in the abdomen towards the back. The kidneys perform a number of important functions. The most important of these is that they filter the blood of waste products generated out of regular metabolic activities of the body, primarily urea, and excretes them out of the body through urine. They help in maintaining the normal pH and water balance of the body. The kidneys also play essential roles in the synthesis of Vitamin D and Red Blood Cells (RBCs).

The Kidney Function Test includes the following tests to monitor kidney function:

·        Blood Urea Nitrogen (BUN)/ Urea:

Blood Urea Nitrogen is a test to measure the amount of urea nitrogen present in the blood. Urea is a nitrogenous by-product of the metabolism of protein and its level in blood serves as an indication of the amount of nitrogen present in blood as urea. In simpler terms, BUN is the measure of the amount of nitrogen present in blood as urea. High BUN levels in the blood can be caused by kidney diseases, dehydration, and obstruction in the urinary tract due to kidney stones, prostate gland enlargement etc.

Urea test measures the level of Urea in blood. Urea is a final waste product formed from the breakdown of proteins. Urea is filtered out of the blood by the kidneys to excrete excess nitrogen present in blood through urine. Excess urea in blood is called uremia and can be caused by a number of conditions including kidney diseases.

·         Uric Acid:

This test measures the level of Uric acid in the blood. Uric acid is a waste product formed from the breakdown of purines, which are essential building blocks of DNA. It is also produced by the metabolism of proteinaceous food, especially red meat. Uric acid is excreted by the kidneys through urine and a small portion through stool. The uric acid test indicates the level of uric acid in the blood and serves as an indirect estimation of kidney function.

The excess uric acid in the blood is called hyperuricemia and causes gout due to the accumulation of uric acid crystals in the synovial fluid between joints. Hyperuricemia also causes the formation of hard lumps of uric acid crystals called tophi under the skin and at the top of the ears. Uric acid crystals can also accumulate in the kidneys and cause kidney stones.

·         Creatinine:

This test measures the level of Creatinine in blood. Creatinine is a waste product formed from the normal breakdown of muscles in the body. Creatinine is almost completely excreted by the kidneys, so their levels in blood serve as an indication of kidney function.

Excess creatinine in the blood can be found due to decreased elimination from the kidneys as well as due to increased creatinine production by muscular breakdown, eating cooked meat, protein supplements, etc.

·         BUN/Creatinine Ratio:

BUN/Creatinine Ratio compares the levels of nitrogen as urea in blood to the levels of creatinine in the blood. This ratio serves as a more accurate representation of kidney function. It is also used to check for dehydration since the BUN level increases in dehydration while creatinine levels remain the same. Low BUN to creatinine ratio can be caused by a low protein diet, liver cirrhosis, rhabdomyolysis (muscle disease), Syndrome of inappropriate antidiuretic hormone secretion (SIADH) as well as during pregnancy.

What Results of Kidney Function Test mean?


Normal levels:

·         Urea:

2.5-7.8 mmol/L

 ·        BUN:

7 to 20 mg/dL

·         Uric Acid:

Adult Female: 2.4 to 6.0 mg/dL

Adult Male: 3.4 to 7.0 mg/dL

Children: 3 to 4 mg/dL

·         Creatinine:

Adult males: 0.6 to 1.2 mg/dL

Adult females: 0.5 to 1.1 mg/dL

·         BUN/Creatinine Ratio:

          12:1 to 20:1

Increased levels of each of these parameters can indicate a number of conditions and not necessarily health disorders. For example, increased creatinine levels can occur due to heavy exercise, consumption of cooked meat, or taking protein supplements apart from kidney diseases. Thus, these parameters are interpreted in combination and further tests are performed to confirm health disorders.

Patient Concerns about Kidney Function Test

Frequently Asked Questions about Kidney Function Test

Q. How is this test performed?
This test is performed on a blood sample. A syringe with a fine needle attached is used to withdraw blood sample from a blood vessel in your arm generally from the inner side of the elbow area. The doctor, nurse or the phlebotomist will tie an elastic band around your arm which will help the blood vessels to swell with blood and hence makes it easier to withdraw blood. You may be asked to tightly clench your fist. Once the veins are clearly visible, the area is cleaned with an antiseptic solution and then the needle is inserted into the blood vessel to collect the sample. You may feel a tiny pinprick during the procedure. Blood sample once collected is then sent to the laboratory.
Q. Is there any risk associated with this test?
There is no risk associated with the test. However, as this test involves a needle prick to withdraw the blood sample, rarely, a patient may experience increased bleeding, hematoma (blood collection under the skin) formation, bruising or infection at the site of needle prick.
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Tests Included in Kidney Function Test(4 tests)

  • Urea/ Blood Urea Nitrogen
  • BUN/Creatinine Ratio
  • Uric Acid
  • Creatinine

Provided By



For over a hundred years, human pathology has been one of the keystones of medicine and rightly so at SRL, we offer our patients world-class Pathology services because their well-being is of the utmost importance to us. Pathology is quite simply the scientific study of the overall response of your body to any foreign influence, i.e., disease. Actually, we use this knowledge to diagnose & subsequently treat your ailment. What we basically do is carefully compare the normal structure and function of a human body (anatomy and physiology) to the abnormal structure and function we witness in an unwell human. Doing this is the most crucial phase & we take note of even the minutest details while adjudging the extent of your ailment because one slip can lead to an incorrect diagnosis, posing serious threat to your health. Our experts ensure that they are extremely careful while analyzing the samples. This is where our advanced technology chips in. SRL is proud to host state-of-the-art equipments based on the latest technology for a speedy and accurate result. We do not take any chances whatsoever with your health & well-being. Avail our Pathology services with no hesitation. You are always in good hands with SRL.

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