Glomerular filtration rate (GFR) and estimation of the GFR (eGFR) in adults

Glomerular filtration is an essential function of the kidney and the glomerular filtration rate (GFR) is generally accepted as the best overall measure of the functioning renal mass in both health and disease. Measurement of the GFR is based on the plasma clearance of a substance by glomerular filtration. In order for the clearance of a substance to be the same as the GFR the clearance marker should be in a stable concentration in the plasma, eliminated from the blood only by the kidneys, freely filtered by glomeruli, not secreted, synthesised or metabolised within the kidney and not reabsorbed from the filtrate. The GFR varies according to age, gender and body size. By convention the GFR is adjusted to a standard body surface area (BSA) of 1.73 m2 for adults.