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Glucose PCT Reabsorption — FRCA Primary MCQ

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HardPhysiology - RenalGlucose PCT ReabsorptionFRCA Primary

In an experimental nephron, SGLT2 is selectively inhibited while SGLT1 and basolateral GLUT2 remain functional. Which change is most likely in a normoglycaemic individual?

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Correct answer: E — More glucose reaches the S3 proximal-tubule segment for reabsorption by SGLT1

The best answer is “More glucose reaches the S3 proximal-tubule segment for reabsorption by SGLT1”. SGLT2 normally performs high-capacity apical glucose uptake in proximal S1/S2. Its inhibition delivers more glucose to S3, where SGLT1 can reabsorb a smaller residual fraction; at therapeutic inhibition the capacity is insufficient for complete rescue, producing glucosuria. GLUT2 is basolateral and GLUT4 is not the relevant renal transporter. NKCC2 and ENaC do not transport glucose.

Reference: RCoA, Primary FRCA syllabus: https://www.rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf; Physiology of renal glucose handling via SGLT1, SGLT2 and GLUT2: https://pmc.ncbi.nlm.nih.gov/articles/PMC6133168/