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Blood Urea Nitrogen Level - Significance and Test Procedures

Published on Oct 11, 2022   -  5 min read


A blood test for urea nitrogen levels provides essential information about kidney health. Let us discuss the significance of knowing about the BUN level.


A blood urea nitrogen test is a vital test to know how well the kidneys function. It is a serum test that measures the amount of nitrogenous urea, a byproduct of protein metabolism in urea. BUN level indicates the extent of renal clearance of urea and nitrogenous waste. It can be due to many factors, such as poor renal function, dehydration, and so on. The normal blood urea nitrogen level is 10 mg/dL to 20 mg/dL. If there is any disturbance in these levels, it could be due to renal failure.

The test can be used to diagnose, screen for, and help treat patients. Blood urea nitrogen alone is often less helpful for these purposes than blood urea nitrogen combined with other renal function tests. A BUN test is usually analyzed in conjunction with a creatinine test to help determine how effectively the kidneys are operating.

What Is BUN Level?

The quantity of urea nitrogen in the blood is measured by a blood urea nitrogen (BUN) test. Urea nitrogen levels are an indicator of how effectively the kidneys are operating. Urea nitrogen is a typical byproduct produced by the body when eating. The liver breaks down the proteins in the daily diet, and as it does so, it produces blood urea nitrogen or BUN. The products are released into the bloodstream by the liver and finally end up in the kidneys.

Healthy kidneys efficiently eliminate BUN, leaving only a trace in the blood. However, for the most part, the kidneys eliminate it by filtering it all out of the body through urine. When the kidneys are not functioning properly, they have difficulty eliminating BUN and thus retaining it in the bloodstream. Therefore the amount of waste product is detected in the blood. If the levels are beyond the usual range, it might indicate that the kidneys or liver are not functioning correctly.

A blood urea nitrogen test is also called urea nitrogen, BUN, or serum urea nitrogen.

Why Is the BUN Test Required?

Sometimes, individuals who seem to have renal issues do not experience symptoms straight away. Sometimes, the doctor may suggest it as a part of the routine check-up. Moreover, the test is also necessary if patients feel they are experiencing any of the following symptoms, such as:

How Is this BUN Test Performed?

A blood sample is used for the test. Blood is drawn from a vein in the arm or hand using a needle by a medical practitioner. When the needle pricks through the skin, it may feel like a tiny sting. It might be painful afterward, but individuals may resume their normal activities immediately. The sample of blood would be sent to a lab for analysis. The findings will be available within a few days.

What Factors May Influence Test Results?

Several factors might influence the test results, possessing a blood urea nitrogen level that is considerably lower or higher than the usual range but does not automatically indicate a problem. The blood urea nitrogen level may be affected by the following factors:

  • Protein-rich diet.

  • Diet deficient in protein.

  • Various drugs, such as steroids and antibiotics.

  • Pregnancy.

  • Aging.

What Are the Risks of Performing This Test?

Having a blood test poses relatively little danger. Patients may suffer some discomfort or bruising where the needle was inserted. These include bleeding, fever, bruises, and dizziness. The tiny sting or pain is felt whenever the needle pricks the arm or hand. Following that, the location may be painful. However, most discomfort will pass quickly.

What Is the Normal Range of Blood Urea Nitrogen Test?

BUN levels are expressed in milligrams per deciliter (mg/dL). What constitutes a normal BUN level is determined by age, and any other possible medical issues constitute a normal BUN level. Usually, a typical reading is between 10 mg/dL to 20 mg/dL.

What Do Abnormal Results Indicate?

Normal BUN levels fluctuate, but a high amount of blood urea nitrogen indicates that the kidneys are not performing properly. However, unusual results may not consistently indicate that there will be a health issue that requires treatment. High amounts of urea nitrogen in the blood may indicate the following:

  • Dehydration.

  • Obstructed urinary tract (blockage from being able to pee).

  • Congestive heart failure (when the heart pumps blood irregularly to the body).

  • Shock.

  • Accidental burns.

  • Stress.

  • Angina pectoris (reduced blood supply to the heart causes this sort of chest discomfort).

  • Bleeding in the intestines (bleeding in the digestive tracts, such as the stomach, intestines, or esophagus).

Low BUN values are quite uncommon. Low BUN levels might mean one of the following:

What Are the Methods of Managing Blood Urea Nitrogen Levels?

By taking care of the body every day, individuals may be able to control their BUN level and live a long and healthy life. The following steps can help:

  • Maintain healthy blood pressure.

  • Keep the blood sugar under control.

  • Every day, consume fresh fruits and vegetables.

  • Consume foods that are low in sodium and saturated fat.

  • Most days of the week, be active for at least 30 minutes.

  • Maintain a healthy weight.

  • Do not use tobacco or smoke.

  • Consult a doctor about medications that may aid in kidney protection.


On the whole, A BUN, or blood urea nitrogen test, is a serum blood test. It may tell a lot about how well the kidneys are working. The kidneys' primary function is to eliminate waste and excess fluids from the body. This waste substance might accumulate in the blood if there is any renal dysfunction. This can lead to major health issues such as high blood pressure, anemia, and heart disease over time.

This test determines the concentration of urea nitrogen in the blood. Urea nitrogen is a waste product removed from the blood by the kidneys. Elevated BUN levels might indicate that the kidneys are not performing properly. This test is performed by drawing blood. The normal range of BUN (blood urea nitrogen) level is 10 mg/dL to 20 mg/dL. Early identification can aid in the effectiveness of therapy. Also, a healthy lifestyle can assist in managing the disease and decreasing the level of blood urea nitrogen.


Last reviewed at:
11 Oct 2022  -  5 min read




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