Creatinine is the waste product of creatine (chemical the body makes to supply energy mainly to the muscles). It is cleared from the body by the kidneys. If there is any abnormality in the functioning of the kidneys the level of creatinine increases in blood because less creatinine is released through the urine.
Certain drugs such as aminoglycosides, cimetidine, cisplatin, and cephalosporins were also found to lower creatinine clearance measurement. Whereas diuretics (water pills that help the body get rid of salt and water) can increase creatinine clearance values.
The creatinine clearance is measured as milliliters per minute (ml/min).