Oncology: tumour lysis syndrome: practice question

A General Medicine 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 Medicine · Oncology: tumour lysis syndrome

Sample item

A 12-year-old boy with Burkitt lymphoma has urine output falling 24 hours after starting chemotherapy. Potassium is 6.4 mmol/L, phosphate 8.2 mg/dL, calcium 6.9 mg/dL, uric acid 14 mg/dL and creatinine is rising. Which measure is most appropriate for preventing and treating this complication?

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

The answer and the reasoning

B. Aggressive intravenous hydration with rasburicase

Rapid lysis of a bulky, highly proliferative tumour releases potassium, phosphate and nucleic acids, causing hyperkalaemia, hyperphosphataemia, secondary hypocalcaemia and hyperuricaemia, with acute kidney injury from urate and calcium phosphate crystals. High-risk patients receive vigorous hydration and rasburicase, which converts uric acid to soluble allantoin. Dialysis is needed for refractory cases.

Option by option

  • A. Allopurinol alone with fluid restriction

    Allopurinol only blocks new urate formation and fluid restriction would worsen kidney injury.

  • B. Aggressive intravenous hydration with rasburicase (correct)

    Correct. Hydration maintains urine flow and rasburicase rapidly removes existing uric acid.

  • C. Intravenous calcium to correct the hypocalcaemia

    Calcium raises calcium-phosphate product and is given only for symptomatic hypocalcaemia.

  • D. Urinary alkalinisation with sodium bicarbonate

    Alkalinisation promotes calcium phosphate precipitation and is no longer recommended.

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 Medicine question

What is the answer to this General Medicine question?

The best answer is B, Aggressive intravenous hydration with rasburicase. Rapid lysis of a bulky, highly proliferative tumour releases potassium, phosphate and nucleic acids, causing hyperkalaemia, hyperphosphataemia, secondary hypocalcaemia and hyperuricaemia, with acute kidney injury from urate and calcium phosphate crystals.

Why is "Allopurinol alone with fluid restriction" not the answer?

Allopurinol only blocks new urate formation and fluid restriction would worsen kidney injury.

Why is "Intravenous calcium to correct the hypocalcaemia" not the answer?

Calcium raises calcium-phosphate product and is given only for symptomatic hypocalcaemia.

Why is "Urinary alkalinisation with sodium bicarbonate" not the answer?

Alkalinisation promotes calcium phosphate precipitation and is no longer recommended.

What concept does this question test?

It tests Oncology: tumour lysis syndrome in General Medicine. High-risk patients receive vigorous hydration and rasburicase, which converts uric acid to soluble allantoin. Dialysis is needed for refractory cases.

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 Oncology: tumour lysis syndrome?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine 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.