Nucleotide metabolism: pyrazinamide and hyperuricaemia: practice question

A Biochemistry 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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Biochemistry · Nucleotide metabolism: pyrazinamide and hyperuricaemia

Sample item

A 40-year-old man on antituberculosis treatment develops an acutely swollen first metatarsophalangeal joint, and serum uric acid is raised. Which drug from the regimen is most likely responsible, by reducing renal tubular secretion of urate?

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

The answer and the reasoning

C. Pyrazinamide

Pyrazinamide is metabolised to pyrazinoic acid, which competes with urate for tubular secretion and reduces its excretion. Hyperuricaemia is common during treatment and can precipitate gout. Ethambutol can also impair urate excretion.

Option by option

  • A. Rifampicin

    Rifampicin causes orange body fluids and enzyme induction, not hyperuricaemia.

  • B. Isoniazid

    Isoniazid causes neuropathy and hepatitis through different mechanisms.

  • C. Pyrazinamide (correct)

    Correct. Its metabolite pyrazinoic acid reduces tubular urate secretion.

  • D. Streptomycin

    Streptomycin causes ototoxicity and nephrotoxicity and is not typically associated with gout.

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 Biochemistry question

What is the answer to this Biochemistry question?

The best answer is C, Pyrazinamide. Pyrazinamide is metabolised to pyrazinoic acid, which competes with urate for tubular secretion and reduces its excretion.

Why is "Rifampicin" not the answer?

Rifampicin causes orange body fluids and enzyme induction, not hyperuricaemia.

Why is "Isoniazid" not the answer?

Isoniazid causes neuropathy and hepatitis through different mechanisms.

Why is "Streptomycin" not the answer?

Streptomycin causes ototoxicity and nephrotoxicity and is not typically associated with gout.

What concept does this question test?

It tests Nucleotide metabolism: pyrazinamide and hyperuricaemia in Biochemistry. Hyperuricaemia is common during treatment and can precipitate gout. Ethambutol can also impair urate excretion.

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 Nucleotide metabolism: pyrazinamide and hyperuricaemia?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry 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.