Renal and acid–base: obstructive uropathy: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Renal and acid–base: obstructive uropathy

Sample item

A 35-year-old with an impacted ureteric calculus has renal colic and falling urine output. Which change in the Starling forces of the glomerulus explains the fall in GFR?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Raised hydrostatic pressure in Bowman capsule

Obstruction raises pressure in the tubule and Bowman space, which opposes filtration and lowers net filtration pressure. Plasma oncotic pressure and capillary hydrostatic pressure are the other main forces.

Option by option

  • A. Raised hydrostatic pressure in Bowman capsule (correct)

    Correct. Raised capsular pressure opposes filtration.

  • B. Fall in capsular oncotic pressure

    Capsular oncotic pressure is negligible since little protein is filtered.

  • C. Fall in plasma oncotic pressure

    A fall in plasma oncotic pressure would raise GFR.

  • D. Rise in glomerular capillary hydrostatic pressure

    A rise in capillary pressure would raise GFR.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is A, Raised hydrostatic pressure in Bowman capsule. Obstruction raises pressure in the tubule and Bowman space, which opposes filtration and lowers net filtration pressure.

Why is "Fall in capsular oncotic pressure" not the answer?

Capsular oncotic pressure is negligible since little protein is filtered.

Why is "Fall in plasma oncotic pressure" not the answer?

A fall in plasma oncotic pressure would raise GFR.

Why is "Rise in glomerular capillary hydrostatic pressure" not the answer?

A rise in capillary pressure would raise GFR.

What concept does this question test?

It tests Renal and acid–base: obstructive uropathy in Physiology. Plasma oncotic pressure and capillary hydrostatic pressure are the other main forces.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Renal and acid–base: obstructive uropathy?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.