Creatinine is a chemical compound left over from energy producing processes in your muscles. Healthy kidneys filter creatinine out of the blood & it exits your body as a waste product in urine. Your doctor prescribes this test if you have signs or symptoms of kidney disease and to screen for kidney disease if you have diabetes, high blood pressure or other conditions that increase the risk of kidney damage. Your results maybe abnormal if you eat too much meat; you have kidney infection, muscle breakdown or obstruction in the urinary tract. This test is also used to calculate Creatinine clearance.