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BUN/Creatinine Ratio Test

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About Our BUN/Creatinine Ratio Test

The BUN/Creatinine ratio blood test is used to diagnose acute or chronic renal (kidney) disease or damage. It may also be used to determine gastrointestinal bleeding or trauma. BUN (blood urea nitrogen) and creatinine are both filtered in the kidneys and excreted in urine. The two together are used to measure overall kidney function.

The BUN/Creatinine ratio is useful in the differential diagnosis of acute or chronic renal disease. Reduced renal perfusion, e.g., congestive heart failure, or recent onset of urinary tract obstruction will result in an increase in BUN/Creatinine ratio. Increased urea formation also results in an increase in the ratio, e.g., gastrointestinal bleeding, trauma, etc. When there is decreased formation of urea as seen in liver disease, there is a decrease in the BUN/Creatinine ratio. In most cases of chronic renal disease the ratio remains relatively normal.

What is a BUN Test?

A Blood Urea Nitrogen (BUN) test measures the amount of nitrogen in your blood, and is used to provide doctors with information on how well your kidneys and liver are functioning. The nitrogen comes from the waste product urea, which is converted from nitrogen and produced in the liver when protein is metabolized after eating. Healthy kidneys then filter the urea and remove other waste products like urea through urination. It is normal to have some urea present in the blood since your liver is always producing it, but too much may indicate an issue with your kidneys.

What is a Creatinine Test?

Creatinine is another type of molecule that is generated from muscle metabolism. Like urea, creatinine is transported through the bloodstream and to the kidneys, where it is also filtered and excreted through the urine. The rate of creatinine formation depends on the individual’s muscle mass. Because muscle mass remains fairly consistent, creatinine levels remain essentially unchanged throughout the day. When results of a creatinine test reveal excess amounts, it could signify impaired kidney function or kidney disease.

What is a BUN/Creatinine Ratio Test?

Once a person performs both a BUN and Creatinine test, doctors can use the combined results to find the BUN-to-creatinine ratio. The BUN and creatinine tests alone are excellent methods of testing liver and kidney health, but together, doctors get a much better understanding of your kidney health and can provide a more accurate diagnosis to kidney-related issues.

Why Take a BUN/Creatinine Ratio Test?

The main reasons to take a BUN/Creatinine Ratio test are to evaluate the health of your kidneys, to diagnose kidney disease, and to monitor the effectiveness of treatments related to kidney disease or damage. BUN/Creatinine ratio test results have been proven to be one of the best ways diagnose acute or chronic renal disease, gastrointestinal bleeding, and urinary tract blockages. Additionally, this test carries essentially no risk.

What do I need to Know Beforehand?

A BUN test can be used to check for severe dehydration, which generally causes BUN levels to rise. Creatinine levels however, do not, which means taking a BUN/Creatinine Ratio Test when dehydrated may skew results. Another factor that can affect BUN results is your protein intake. High-protein diets may cause abnormally high BUN levels, while low-protein diets may lead to low BUN levels . It is best to be properly hydrated and consume a normal amount of protein before taking the BUN/Creatinine Ratio Test.

How Are the Tests Taken?

Testing with Healthlabs is as simple as it is quick. After you have purchased a BUN/Creatinine test and traveled to the lab you selected using our lab finder, a lab technician will perform a simple blood test. The technician inspects your arm for vein visibility first, where he then chooses a spot to draw the blood, cleans the area with antiseptic, and wraps an elastic band around your upper arm in preparation for collection. He carefully injects a sterile need into the vein and draws blood. The entire process, depending on how busy the lab is, should take about 5-10 minutes.

What your BUN/Creatinine Ratio Test Results mean?

A BUN/Creatinine ratio is found by dividing the BUN count with the creatinine count. Because the body produces much more BUN than creatinine, the ideal ratio lies somewhere between 10:1 and 20:1. Results that are higher than this range mean there is an excess of BUN in the blood, which could mean your kidneys are not getting the proper blood flow. An excessively high ratio could also reveal conditions such as congestive heart failure, gastrointestinal bleeding, or severe dehydration. A BUN/Creatinine ratio that falls below the suggested range could indicate liver disease or malnutrition.

Medically Reviewed by: 2019-05-17

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