Which substance is used to measure the glomerular filtration rate (GFR) in the human kidney through plasma clearance?

Explanation

The glomerular filtration rate (GFR) is best assessed by measuring the plasma clearance of inulin, as it is freely filtered by the glomerulus and neither reabsorbed nor secreted by the renal tubules. PAH is used to estimate renal plasma flow, urea and glucose levels are influenced by tubular handling, and creatinine clearance is an approximate measure but less accurate than inulin.