Creatinine is a chemical waste product produced by muscles during normal metabolism. It forms when creatine, a substance important for muscle energy production, breaks down
. Because creatinine is produced at a relatively constant rate depending on muscle mass, its level in the blood is a useful indicator of kidney function
. Healthy kidneys filter creatinine out of the blood and excrete it in urine. If the kidneys are not working properly, creatinine accumulates in the blood, leading to elevated levels
. Measuring creatinine in blood or urine helps healthcare professionals assess how well the kidneys are filtering waste
. A creatinine test is commonly ordered to:
- Detect kidney disease or damage
- Monitor kidney function over time, especially in people with diabetes, high blood pressure, or other risk factors
- Adjust medication dosages that may affect kidneys
- Evaluate the function of a transplanted kidney
Normal creatinine levels vary by age, sex, and muscle mass but typically range around 0.7 to 1.2 mg/dL for adult males and 0.5 to 1.0 mg/dL for adult females
. Elevated creatinine indicates impaired kidney function, while low levels may suggest muscle loss or other issues
. In summary, creatinine is a muscle metabolism byproduct filtered by the kidneys, and its blood or urine levels are key markers used to evaluate kidney health and function
