Which substance is considered the gold standard for measuring glomerular filtration rate experimentally?

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

Explanation

Inulin is freely filtered at the glomerulus and is neither reabsorbed nor secreted anywhere along the nephron, so its clearance equals GFR exactly. PAH is filtered and avidly secreted, so its clearance approximates renal plasma flow, not GFR. Glucose is completely reabsorbed below its transport maximum, giving near-zero clearance, and urea is partially reabsorbed, so its clearance underestimates GFR.

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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