BUN and creatinine tests are common medical lab tests used to assess kidney function. The BUN, or blood urea nitrogen test, measures amounts of nitrogen in your blood. A creatinine test is used to check for how well your kidneys are filtering cellular waste products from your blood. During a physical exam or for a specific diagnosis, your doctor may order these tests to best determine the state of your health and to decide how to best treat your condition.
Kidney Tests
Your doctor may test your kidney function for a variety of reasons. Kidney function is disrupted in a number of chronic conditions, including diabetes and high blood pressure. The results of a kidney test can give your doctor important insights into such conditions. In addition, many prescription drugs have effects on the kidneys. Before prescribing some drugs, your doctor may want to ensure that your kidneys are healthy enough to process and react to them.
Blood Urea Nitrogen
MayoClinic.com explains that the BUN test measures how much urea-based nitrogen is in your blood. After you eat a typical meal, your body processes proteins from food into smaller chemical components used to build cells and also for energy. When you metabolize proteins, your cells also form nitrogen-based waste products, such as ammonia, which are eventually converted into urea. As urea travels through your blood, it normally gets filtered out by your kidneys and then excreted. If your kindeys are not working properly, or, if you have a high protein diet, your BUN levels may be high. Low BUN levels may indicate liver problems or malnutrition.
Creatinine
Creatinine tests measure how well your kidneys are filtering waste products from your blood, according to MayoClinic.com. Creatinine is a breakdown product of creatine that is formed during muscle metabolism. When your kidneys are properly functioning, they filter creatinine from your blood. By checking to see how much creatinine is in your blood or urine, your doctor can determine how well your kidneys are filtering out waste products from your blood. Creatinine tests are often used to check for kidney function in people with diabetes.
Getting the Tests
MedlinePlus explains that getting a BUN or creatinine test is straightforward. If your doctor orders such a test, a medical professional will simply draw a small amount of blood from a vein in your arm. This blood will then be sent to a laboratory where it will be analyzed for urea or creatinine levels. Sometimes, creatinine levels are analyzed in the urine as well as the blood. If such a test is required, you will be asked to supply a urine sample. If you are having a BUN or creatinine test, be sure to tell your doctor if you are taking any prescription drugs, as these may affect your test results.
