Why is bun elevated

On a normal diet, we produce about 12 g of urea each day [ 2 ]. The bulk of the urea , about 10 g each day, is eliminated by the kidneys [ 2 ]. Being a diuretic, urea helps the kidneys quickly flush water and other compounds [ 4 , 5 ]. A small amount of urea less than 0. During exercise , a substantial amount may be lost through sweat [ 2 ]. BUN levels represent the balance between [ 6 ]:. However, creatinine is a much more reliable marker of kidney function.

BUN is far more likely to be affected by dietary and physiologic conditions unrelated to kidney function [ 2 ]. Your healthcare provider will compare your lab test results with reference values to see if any of your results fall outside the range of expected values. By doing so, you and your healthcare provider can gain clues to help identify possible conditions or diseases. In Europe, the whole urea molecule is measured , whereas in the United States only the nitrogen component of urea is measured the blood or serum urea nitrogen, i.

The BUN is roughly one-half of the blood urea [ 3 ]. The range is wide because of normal variations due to protein intake, protein breakdown, state of hydration, liver urea production, and urea elimination by the kidneys [ 3 ].

Decreased or elevated BUN concentrations are usually seen in pregnancy [ 7 , 8 ]. The level of creatinine in your blood also tells how well your kidneys are working. The urea nitrogen test is often ordered for people who are experiencing signs and symptoms of kidney disorders. These symptoms can include:. In rare cases, people become lightheaded or faint after having blood drawn. Notify your doctor if you experience any unexpected or prolonged side effects after the test.

A BUN test is a quick and simple blood test commonly used to evaluate kidney function. If your doctor suspects you have a kidney disorder or another health condition, they will order additional tests to confirm a diagnosis and determine the cause.

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The test measures the amount of urea nitrogen in your blood. Urea nitrogen is one of the waste products removed from your blood by your kidneys. Higher than normal BUN levels may be a sign that your kidneys aren't working efficiently. People with early kidney disease may not have any symptoms. A BUN test can help uncover kidney problems at an early stage when treatment can be more effective. A BUN test is often part of a series of tests called a comprehensive metabolic panel, and can be used to help diagnose or monitor a kidney disease or disorder.

Your health care provider may order a BUN test as part of a routine check-up or if you have or are at risk for a kidney problem. Although early kidney disease usually does not have any signs or symptoms, certain factors can put you at a higher risk. These include:. In addition, your BUN levels may be checked if you are experiencing symptoms of later stage kidney disease, such as:. A health care professional will take a blood sample from a vein in your arm, using a small needle.

After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes. You don't need any special preparations for a BUN test.