The creatinine and BUN, or blood urea nitrogen, blood tests are usually ordered as a part of a basic or comprehensive metabolic panel to assess kidney function. These tests may be ordered as part of a routine physical exam or to monitor declining kidney function in people with kidney diseases. These tests may also be used to determine if your kidneys are healthy enough to withstand procedures that use drugs that may damage the kidneys.
Creatinine
Creatinine is a waste product created when your body breaks down creatine, a substance that helps your body produce energy. According to Lab Tests Online, almost all of the creatinine in your body is removed from your body by your kidneys. Because of this, creatinine levels in the blood are relatively low when the kidneys are working properly. Normal creatinine values generally fall between 0.8 and 1.4 mg/dL. Normal values vary slightly based on an individual's muscle mass.
BUN
Urea nitrogen is a waste product that forms when your body breaks down protein. Urea nitrogen travels through your body in your blood until it reaches the kidneys and is removed by the body. A BUN, or blood urea nitrogen, test can be used to measure the amount of urea nitrogen in your blood. A normal BUN usually falls between 7 and 20 mg/dL.
Increased Creatinine and BUN Levels
Increased creatinine and BUN levels usually indicate an underlying condition that affects kidney function. Possible conditions may include acute or chronic kidney failure, inflammation of the blood vessels in the kidneys, bacterial infection in the kidneys, kidney stones or decreased blood flow to the kidneys due to dehydration, shock, heart failure or diabetes.
Occasionally, elevated levels of creatinine and BUN indicate other conditions rather than impaired kidney function. An elevated creatinine level may be caused by muscle injury. Elevated BUN levels can occur as a result of gastrointestinal bleeding or extremely high intake of dietary protein.
Considerations
While creatinine and BUN tests can indicate the presence of an underlying condition, they cannot determine the specific condition. If your creatinine or BUN test is abnormal, further testing is necessary to determine the condition causing the increase in your levels.
Pregnancy may cause decreases in creatinine levels and increases or decreases in BUN levels. This is considered normal and is not a cause for concern.
