Explain the Serum Creatinine Test

Creatinine is a breakdown product of creatine, an important component of muscle. A serum creatinine test measures the amount of creatinine in the blood. The production of creatinine depends on person's size and the muscle mass, which varies very little. Creatinine is excreted exclusively by the kidneys, and its level in the blood is proportional to the glomerular filtration rate.

The serum creatinine level provides a more sensitive test of kidney function than BUN because kidney impairment is the most common cause of elevated creatinine. The normal (usual) value for this test is 0.8 to 1.4 mg/dl. Females have a lower creatinine than males due to decreased muscle mass. The greater-than-normal and lower than normal values indicate various diseases.