Creatinine is a waste output of creatine. The body makes creatine to supply energy to the muscles and is removed from the body by the kidneys. If the kidneys are not functioning properly, the level of creatinine in the urine will decrease. This test is used to see how well the kidneys are working.
If results are outside of the normal range, this could be a result of the following:
- kidney disease, infection, or failure
- kidney stones
- late-stage muscular dystrophy
- myasthenia gravis