MPAS Common Laboratory Tests: Blood Practice Test

Creatinine is a waste product produced by muscles and cleared from the blood by the kidneys. The level of creatinine in the blood rises when the kidneys’ filtering ability declines, meaning the glomerular filtration rate (GFR) goes down. So an elevated creatinine level points to decreased renal function rather than improved or unchanged function.

Keep in mind that dehydration can sometimes transiently raise creatinine by reducing blood flow to the kidneys, but the core interpretation in most contexts is impaired kidney filtration. Clinically, creatinine is often used with estimates of GFR to gauge how well the kidneys are functioning.