Which substance is regarded as the gold standard for the measurement of glomerular filtration rate?

• A Creatinine
• B Urea
• C Para-aminohippuric acid
• D Inulin ✓

Explanation

Inulin is a fructose polysaccharide that is freely filtered at the glomerulus and is neither reabsorbed, secreted nor metabolised by the tubule, so its clearance equals the true GFR. Creatinine clearance slightly overestimates GFR because tubular secretion adds to filtration, and urea clearance underestimates it because of partial tubular reabsorption. Para-aminohippuric acid clearance measures effective renal plasma flow, not GFR.

Reference: Harper's Illustrated Biochemistry, 31st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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