Blood Urea Nitrogen (BUN)

The BUN test is primarily used, along with the creatinine test, to evaluate kidney function in a wide range of circumstances, to help diagnose kidney disease, and to monitor patients with acute or chronic kidney dysfunction or failure. It also may be used to evaluate a person’s general health status when ordered as part of a basic metabolic panel (BMP) or comprehensive metabolic panel (CMP).


The creatinine blood test is used along with a BUN (blood urea nitrogen) test to assess kidney function. Both are frequently ordered as part of a basic or comprehensive metabolic panel (BMP or CMP), groups of tests that are performed to evaluate the function of the body’s major organs. BMP or CMP tests are used to screen healthy people during routine physical exams and to help evaluate acutely or chronically ill patients in the emergency room and/or hospital. If the creatinine and BUN tests are found to be abnormal or if you have an underlying disease, such as diabetes, that is known to affect the kidneys, then these two tests may be used to monitor the progress of kidney dysfunction and the effectiveness of treatment. Blood creatinine and BUN tests may also be ordered to evaluate kidney function prior to some procedures, such as a CT (computed tomography) scan, that may require the use of drugs that can damage the kidneys.


The eGFR test is used to screen for and detect early kidney damage and to monitor kidney status. It is performed by ordering a creatinine test and calculating the eGFR. The creatinine test is ordered frequently as part of a routine comprehensive metabolic panel (CMP)or basic metabolic panel (BMP), or along with a blood urea nitrogen (BUN) test whenever a doctor wants to evaluate the status of the kidneys. It is ordered to monitor those with known kidney disease and those with conditions such as diabetes and hypertension that may lead to kidney damage. eGFR of 60 or higher (>60) is in the normal range. Below 60 (<60) may mean kidney disease, and 15 or lower may mean kidney failure.


Currently, the main use for LDH is as a general indicator of the existence and severity of acute or chronic tissue damage and, sometimes, as a monitor of progressive conditions such as some cancers, kidney disease, and liver disease. It used to be ordered to help diagnose and monitor a heart attack, but the troponin test has largely replaced LDH in this role. LDH isoenzymes may be used in differential diagnosis to help determine which organs are likely to be involved.

See Also C-Reactive Protein (CRP) High Sensitivity (Cardiac Risk Assessment)