BUN

This test measures the amount of urea nitrogen in the blood.

What is urea?

Urea is a waste product formed in the liver as a result of protein breakdown. This urea is then released into the blood by the liver. Normally, it is then removed from the blood by the kidneys. Kidneys filter urea and it gets removed from the body through urination.

Why this test is performed?

This test is one among many tests used to evaluate your kidney function. Your doctor may ask to perform this test if you experience any signs and symptoms of kidney damage such as fatigue, bloody, coffee-colored or foamy urine, frequent urination, swelling on face, arms, stomach, legs, feet or around eyes, nausea or vomiting, weakness, muscle cramps etc. You may be advised to undergo this test if you have diabetes, heart disease, high blood pressure or a family history of kidney problems. Your doctor may also ask to perform this test to check the effectiveness of dialysis treatment in case if you are receiving hemodialysis or peritoneal dialysis. This test may also be performed with other blood tests to rule out other medical conditions, such as liver damage, urinary tract obstruction, congestive heart failure or gastrointestinal bleeding. But these conditions are not diagnosed by this test.

Frequency:

If you have a family history of kidney problems, your doctor may ask you to perform this test on a 6-monthly basis or a yearly basis. Patients with kidney disorders should perform this test on a regular basis, as instructed by the doctor.

Precautions:

Certain medicines that show high BUN levels are amphotericin B, vancomycin, cephalosporins, diuretics, methyldopa, rifampin, carbamazepine, tetracyclines etc.

If the test result falls in the normal reference range generally no medical intervention is necessary. The BUN levels may be normal even when if one kidney is damaged and the other is functional.

High levels of blood urea nitrogen (BUN) indicate that your kidneys are not working properly. Symptoms of kidney damage are fatigue, bloody, coffee-colored or foamy urine, frequent urination, swelling on face, arms, stomach, legs, feet or around eyes, nausea or vomiting, weakness, muscle cramps etc. Other causes of high BUN levels are conditions that result in poor blood flow to the kidneys such as heart failure, gastrointestinal bleeding, shock, severe burns, or stress and urinary tract obstruction. Use of certain medications like antibiotics, dehydration and a high protein diet may also result in high BUN levels in the blood.

Low levels of blood urea nitrogen (BUN) are not very common. This can be due to liver disease or damage, malnutrition, overhydration or lack of protein in the diet. But these conditions are not diagnosed by this test. Women who are on the second or third trimester of pregnancy may also show low BUN levels.

If you have higher or lower than normal levels of BUN test results consult your doctor for further instructions. Based on the test results, your doctor may advise appropriate medical treatments, lifestyle modifications, or further diagnostic tests.