Blood urea nitrogen
The blood urea nitrogen test (BUN) measures the nitrogen amount in your blood. This nitrogen in the blood comes from the waste product urea. Urea is formed in the protein breakage process in the liver. The removal of urea is obtained through the urine. BUN test checks the functioning ability of the kidneys. In case your kidneys are unable to remove the urea from your blood with full efficiency, BUN level of your blood gets increased. If you have liver disease or your liver gets damaged, BUN level in your liver may be decreased.
Ratio of blood urea nitrogen to creatinine:
Mostly BUN test is done in combination with creatinine test. The working status of kidneys is also depicted by creatinine test. If level of creatinine is found high, then it is predicted that your kidneys are not working well. In this case BUN level and creatinine ration is depicted to predict conditions like dehydration.
NeedNecessity of blood urea nitrogen test is in following conditions:
- Determine the normal functioning of kidneys
- Determine the degradation of your kidney disease
- Check up the kidney disease treatment
- Find out if severe dehydration is present
Procedure Do not eat the diet high in meat or other protein before having the blood urea nitrogen BUN test. Your upper arm is wrapped with elastic belt to stop the blood flow. The veins below the band get bigger and make the needle easy to insert. The site of the needle insertion is cleaned with alcohol and the needle is put into the vein. Sometimes, more than one needle sticks are necessary. The tube is attached to a needle to fill the blood in it. The band is removed from your arm when adequate blood amount is collected. The gauze pad or cotton ball is applied over the needle site after removing the needle. At first, pressure is applied to that site for some time and then bandage is wrapped over it.
ResultResult may have different normal values in different labs.
- Normal BUN: 10-20 milligrams per deciliter (mg/dl) or 3.6-7.1 milimoles per liter (mmol/L)
- Bun to creatinine ration above 12 months of age: 10:1, 20:1
- Babies less than 12 months of age: up to 30:1
If BUN values are high then they may indicate kidney injury or disease. Some medicines are also responsible for the high value of BUN into the blood. A high protein diet also leads you to high BUN values. If the rise in BUN values is observed, then there may be kidney problems due to diabetes. If BUN and creatinine ratio is high then there may be sudden kidney failure may be observed. The high ratio is also the indication of the bleeding in the digestive or respiratory tract.
Low BUN values cause by low protein diet, severe liver damage or malnutrition. Having excessive liquids may cause overhydration.
Consideration There are rare complications while taking out blood from the vein. Sometimes, a bruise or a puncture may be developed at the needle site. This risk may be reduced by giving pressure on the needle site for long time. If condition of vein inflammation arises after the test then you have to apply warm compresses daily for several times. This inflammation condition is known as the phlebitis. People having the problems of bleeding disorders may suffer with the problem of continued bleeding.
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