A measurement of creatinine can be employed for screening, diagnosis, and/or monitoring of kidney problems. Creatinine is a chemical compound left over from energy-producing processes in your muscles. Healthy kidneys filter creatinine out of the blood. Creatinine exits your body as a waste product in urine.
Creatinine blood tests are usually performed along with several other laboratory tests, including a blood urea nitrogen (BUN) test and a basic metabolic panel (BMP) or comprehensive metabolic panel (CMP). These tests are done during routine physical exams to help diagnose certain diseases and to check for any problems with your kidney function.
- Your doctor may order a creatinine blood test to assess your creatinine levels if you show signs of kidney disease. These symptoms include:
- Fatigue and trouble sleeping
- A loss of appetite
- Swelling in the face, wrists, ankles, or abdomen
- Lower back pain near the kidneys
- Changes in urine output and frequency
- High blood pressure
- Kidney problems can be related to different diseases or conditions, including:
- Glomerulonephritis, which is an inflammation of the glomeruli due to damage
- Pyelonephritis, which is a bacterial infection of the kidneys
- Prostate disease, such as an enlarged prostate
- Blockage of the urinary tract, which may be due to kidney stones
- Decreased blood flow to the kidneys, which may be caused by congestive heart failure, diabetes, or dehydration
- The death of kidney cells as a result of drug abuse
- Streptococcal infections, such as poststreptococcal glomerulonephritis.
Aminoglycoside medications, such as gentamicin (Garamycin, Gentasol), can also cause kidney damage in some people. If you’re taking this type of medication, your doctor may order regular creatinine blood tests to make sure your kidneys remain healthy.
Screening is trying to identify health problems before there are any signs or symptoms. In people who are at higher risk of kidney problems, a creatinine test may be used to try to detect a problem early.
Diagnosis involves testing to determine the underlying cause after symptoms have started. Creatinine may be measured to help diagnose symptoms that can be associated with kidney problems such as swelling in the feet, urinary changes, loss of appetite, and fatigue. A measurement of creatinine may also be included in a panel of tests for more general symptoms or when evaluating a patient in the emergency room.
Monitoring is how doctors track a patient’s condition over time. For people who have kidney disease, a creatinine test can provide information about how the disease may be progressing. Tests of kidney function can also be used to watch for potential side effects when a patient is prescribed medications that can affect the kidneys.
In many cases, screening, diagnosis, and monitoring of kidney problems involve more than just a creatinine measurement. For example, creatinine may be tested in order to calculate the estimated glomerular filtration rate (eGFR), which is an assessment of how effectively the kidneys are filtering the blood.
Note: Some drugs may increase your creatinine levels without causing kidney damage and interfere with your test results. Let your doctor know if you take:
- cimetidine (Tagamet, Tagamet HB)
- nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin (Bayer) or ibuprofen (Advil, Midol)
- chemotherapy drugs
- cephalosporin antibiotics, such as cephalexin (Keflex) and cefuroxime (Ceftin)