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Urea Analysis

Urea is a chemical waste that the liver releases into the bloodstream. Doctors use tests such as the BUN , or blood urea nitrogen, test, and the urea breath test to analyze urea levels in the body. Abnormally high or low urea measurements may indicate a medical disorder. Prescription drugs can cause a patient's urea levels to become unusually high or low.

  1. Urea

    • Urea, or urea nitrogen, is a waste product that is produced in the liver. The liver breaks down proteins into ammonia. Nitrogen from ammonia combines with other chemicals to form urea. An individual's liver releases urea into the bloodstream and the kidneys filter urea from the blood. The kidneys convert urea into urine and remove it from the body during urination. Doctors use an urea analysis to find indications of medical disorders that may involve the liver or kidneys.

    BUN Test

    • The BUN test is a blood test that measures urea levels in a patient’s blood. A health care professional draws blood from a patient’s arm and send the blood to a laboratory for analysis. According to the U.S. National Library of Medicine, patients with normal BUN test results usually have between 7 and 20 milligrams of urea nitrogen per deciliter of blood. A doctor may order this test (and a creatinine test) if he suspects that a patient has kidney failure.

    Abnormal BUN Results

    • People with abnormally high BUN test results may have a serious medical condition, such as gastrointestinal bleeding, congestive heart failure or a heart attack. Kidney disease, kidney failure and urinary tract obstruction can also cause an individual to accumulate high levels of urea in the bloodstream. Patients who are over-hydrated, people with malnutrition and individuals with liver failure may have low BUN levels on this blood test.

    BUN Drug Interactions

    • Several drugs, such as tetracyclines, high doses of aspirin and thiazide diuretics, can cause a patient’s blood urea levels to increase. Probenecid, rifampin and propranolol can also increase blood urea measurements. Users of streptomycin and chloramphenicol can cause reduced blood levels of urea. Patients should inform their doctors of all prescription and non-prescription medications they take so that doctors can consider the effects of drugs on the patient's urea analysis.

    Urea Breath Test

    • The urea breath test measures the amount of a specific carbon dioxide isotope in a patient’s breath to determine the presence of Helicobacter pylori bacteria. The patient swallows a capsule that contains urea. Helicobacter pylori bacteria break down urea and convert it to a carbon dioxide isotope. A special device measures the amount of carbon dioxide isotope in the air that the patient exhales. Test results that show no carbon dioxide isotope in the patient’s breath indicate that the Helicobacter pylori bacteria are not present in the patient’s stomach.

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