Renal: Liddle syndrome: 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: Liddle syndrome

Sample item

A 16-year-old has hypertension, hypokalaemia and metabolic alkalosis, with low plasma renin and low aldosterone. Spironolactone does not correct the problem. Which drug is likely to work?

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

The answer and the reasoning

A. Amiloride

Liddle syndrome is a gain-of-function mutation of the epithelial sodium channel (ENaC) in the collecting duct, so sodium is reabsorbed and potassium lost regardless of aldosterone. Direct ENaC blockers (amiloride, triamterene) correct it, while aldosterone antagonists do not because aldosterone is already low.

Option by option

  • A. Amiloride (correct)

    Correct. Amiloride blocks the overactive channel directly.

  • B. Dexamethasone

    Dexamethasone treats glucocorticoid-remediable aldosteronism, in which aldosterone is high.

  • C. Furosemide

    Furosemide would increase distal sodium delivery and worsen potassium loss.

  • D. Hydrochlorothiazide

    A thiazide would also increase potassium wasting and not block ENaC.

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, Amiloride. Liddle syndrome is a gain-of-function mutation of the epithelial sodium channel (ENaC) in the collecting duct, so sodium is reabsorbed and potassium lost regardless of aldosterone.

Why is "Dexamethasone" not the answer?

Dexamethasone treats glucocorticoid-remediable aldosteronism, in which aldosterone is high.

Why is "Furosemide" not the answer?

Furosemide would increase distal sodium delivery and worsen potassium loss.

Why is "Hydrochlorothiazide" not the answer?

A thiazide would also increase potassium wasting and not block ENaC.

What concept does this question test?

It tests Renal: Liddle syndrome in Physiology. Direct ENaC blockers (amiloride, triamterene) correct it, while aldosterone antagonists do not because aldosterone is already low.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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: Liddle syndrome?

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.