Creatinine is a waste product that forms when creatine (a supplier of energy to the muscles) breaks down. Creatinine levels are often assessed to determine how well the kidneys are working or before and after dialysis to monitor effectiveness of treatment. Frequently, healthcare providers will use your blood creatinine level, along with your age, race, sex, and other factors to calculate your glomerular filtration rate (GFR). The GFR is considered to be the best measure of kidney function. Our kidneys are full of small blood-filtering structures called nephrons. The nephrons remove waste products, excess water, and other impurities from the blood. The toxins are then stored in the bladder and removed in urine. Creatinine is one of the substances that our kidneys normally remove from the body. An abnormally high level of creatinine in the blood may indicate that the kidneys are damaged or impaired. Creatinine tests are often run along with several other tests, including a blood urea nitrogen test, a basic metabolic panel, or a comprehensive metabolic panel to evaluate major organ systems. Some signs and symptoms of kidney dysfunction include:
- Fatigue and trouble sleeping
- Loss of appetite
- Swelling in the face, wrist, ankles, or abdomen
- Lower back pain near the kidneys
- Changes in urine output and frequency
- High blood pressure
- Nausea / vomiting
Normal Ranges mg/dL:
Decreased blood creatinine levels may indicate lower muscle mass, which can be caused by diseases like muscular dystrophy or by aging. A diet very low in protein can have the same effect, and in rare cases low creatinine levels may be due to severe liver disease.
It is worth noting that creatinine blood levels are generally slightly lower during pregnancy.
Increased creatinine levels in the blood suggest kidney disease or other conditions that affect kidney function, including:
- Bacterial infection of the kidneys
- Reduced blood flow to the kidneys due to shock, dehydration, congestive heart failure, or complications of diabetes
- Urinary tract obstruction due to kidney stones or prostate disease
- A high protein diet
Creatinine blood levels may also temporarily increase as a result of muscle injury.
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