BUN/Creatinine Ratio

Having a small amount of urea nitrogen in your blood is normal. But higher-than-normal BUN levels may be a sign that your kidneys aren't working well. If you have kidney disease, this waste material can build up in your blood and may lead to serious health problems, including high blood pressure, anemia, and heart disease.

The BUN/creatinine ratio compares your BUN level with your creatinine level. Looking at the two together can give your provider extra clues about what is going on with your kidneys, hydration, or liver. The ratio is especially helpful for telling apart different causes of kidney trouble, including sudden (acute) versus longer-term (chronic) kidney problems.

People with early kidney disease may not have any symptoms. A BUN test can help uncover kidney problems early, when treatment can be more effective.

Normal BUN levels can vary, but generally, a high blood urea nitrogen level is a sign that your kidneys are not working well. But abnormal results don't always mean that you have a medical condition that needs treatment.

BUN levels can vary according to your sex. They also usually increase with age. A few other reasons your BUN level might be higher than normal include dehydration, burns, certain medicines, a high-protein diet, or a recent heart attack.

A few other reasons your BUN levels might be lower than normal include a lack of protein in your diet, malnutrition, or liver disease.

A higher BUN/creatinine ratio can point to things like dehydration, reduced blood flow to the kidneys, or a blockage in the urinary tract. It can also be raised when your body is making more urea than usual. A lower ratio can sometimes be seen with liver disease, when the liver makes less urea than normal.

To learn what your results mean, talk to your provider.