Neoplasia: oncologic emergencies: practice question

A Pathology 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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Pathology · Neoplasia: oncologic emergencies

Sample item

A 7-year-old child with Burkitt lymphoma receives chemotherapy. After 24 hours, urine output falls, with potassium 6.8 mEq/L, high phosphate, low calcium and uric acid 14 mg/dL. Which drug most rapidly lowers the established uric acid?

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

The answer and the reasoning

B. Rasburicase

This is tumour lysis syndrome, with release of potassium, phosphate and nucleic acid breakdown products from dying tumour cells, causing hyperkalaemia, hyperphosphataemia, secondary hypocalcaemia and hyperuricaemia. Rasburicase converts uric acid to the soluble allantoin and acts quickly. It is contraindicated in G6PD deficiency.

Option by option

  • A. Allopurinol

    Allopurinol blocks xanthine oxidase and prevents new uric acid but does not remove what is already formed.

  • B. Rasburicase (correct)

    Rasburicase breaks down existing uric acid into soluble allantoin.

  • C. Probenecid

    Probenecid increases urinary uric acid excretion and could worsen urate nephropathy in this setting.

  • D. Sodium bicarbonate

    Alkalinisation is no longer routine, since it adds the risk of calcium phosphate precipitation and does not lower uric acid.

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 Pathology question

What is the answer to this Pathology question?

The best answer is B, Rasburicase. This is tumour lysis syndrome, with release of potassium, phosphate and nucleic acid breakdown products from dying tumour cells, causing hyperkalaemia, hyperphosphataemia, secondary hypocalcaemia and hyperuricaemia.

Why is "Allopurinol" not the answer?

Allopurinol blocks xanthine oxidase and prevents new uric acid but does not remove what is already formed.

Why is "Probenecid" not the answer?

Probenecid increases urinary uric acid excretion and could worsen urate nephropathy in this setting.

Why is "Sodium bicarbonate" not the answer?

Alkalinisation is no longer routine, since it adds the risk of calcium phosphate precipitation and does not lower uric acid.

What concept does this question test?

It tests Neoplasia: oncologic emergencies in Pathology. Rasburicase converts uric acid to the soluble allantoin and acts quickly. It is contraindicated in G6PD deficiency.

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 Neoplasia: oncologic emergencies?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.