Urology: cystine stones: practice question

A General Surgery 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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General Surgery · Urology: cystine stones

Sample item

Urine microscopy shows hexagonal crystals and the sodium nitroprusside test is positive. What treatment helps prevent recurrence?

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

The answer and the reasoning

C. High fluid intake, urine alkalinisation and tiopronin

Cystinuria is an autosomal recessive defect of the dibasic amino acid transporter (cystine, ornithine, lysine, arginine). Cystine stones are radio-opaque due to sulphur, and prevention needs high urine volume, pH above 7, and thiol agents such as tiopronin.

Option by option

  • A. Allopurinol

    Allopurinol is for uric acid or hyperuricosuria.

  • B. Thiazide diuretics

    Thiazides reduce urinary calcium.

  • C. High fluid intake, urine alkalinisation and tiopronin (correct)

    Correct. This is the standard preventive regime.

  • D. Calcium restriction alone

    Calcium restriction does not affect cystine.

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 General Surgery question

What is the answer to this General Surgery question?

The best answer is C, High fluid intake, urine alkalinisation and tiopronin. Cystinuria is an autosomal recessive defect of the dibasic amino acid transporter (cystine, ornithine, lysine, arginine).

Why is "Allopurinol" not the answer?

Allopurinol is for uric acid or hyperuricosuria.

Why is "Thiazide diuretics" not the answer?

Thiazides reduce urinary calcium.

Why is "Calcium restriction alone" not the answer?

Calcium restriction does not affect cystine.

What concept does this question test?

It tests Urology: cystine stones in General Surgery. Cystine stones are radio-opaque due to sulphur, and prevention needs high urine volume, pH above 7, and thiol agents such as tiopronin.

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 Urology: cystine stones?

Learn classic signs and eponyms alongside what they diagnose. Then use the flashcards and the other General Surgery 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.