Measurement of glomerular filtration rate (GFR)

Abstract

Glomerular filtration rate (GFR) is the volume of plasma filtered by the glomeruli in millilitres per minute. It can be measured as the clearance of any substance that is filtered but not actively secreted or reabsorbed by the tubules. The fructose polymer inulin is the traditional GFR marker which meets these criteria, but is difficult to assay in clinical practice. Endogenous markers are used for day-to-day practice, but exogenous markers are used if a more accurate measure is required. GFR is proportional to body surface area (BSA) and is therefore expressed as mL/min/1.73 m2, the latter being the average adult BSA. Normal values are generally >90 mL/min/1.73 m2.