What is creatine in the kidneys?

Creatine is a substance formed by the metabolic system when changing food into energy, according to WebMD. It breaks down into another substance known as creatinine. Healthy kidneys rid the body of this substance by passing it through urine.

A high creatinine level in the blood can be indicative of improperly functioning kidneys, states WebMD. Doctors typically administer creatinine clearance tests to determine if an individual has healthy kidneys or to monitor kidney disease.

The amount of creatinine in a body is partially dependent on the amount of muscle tissue in the body, according to WebMD. Because of this, women typically have lower creatinine levels.