Antimicrobials: ethionamide hypothyroidism: practice question

A Pharmacology 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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Pharmacology · Antimicrobials: ethionamide hypothyroidism

Sample item

A patient on a regimen for drug-resistant tuberculosis develops fatigue, weight gain and cold intolerance. TSH is 38 mIU/L with a low free T4. Which drug is the likely cause?

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

The answer and the reasoning

B. Ethionamide

Ethionamide, like para-aminosalicylic acid, can inhibit thyroid hormone synthesis and cause hypothyroidism, so thyroid function is monitored and levothyroxine given if needed. It also causes severe gastric intolerance and hepatitis. The other drugs have different toxicities.

Option by option

  • A. Levofloxacin

    Levofloxacin causes tendinopathy, QT prolongation and dysglycaemia.

  • B. Ethionamide (correct)

    Correct. Ethionamide interferes with thyroid hormone synthesis.

  • C. Bedaquiline

    Bedaquiline causes QT prolongation, nausea and hepatic enzyme rise.

  • D. Pyrazinamide

    Pyrazinamide causes hepatotoxicity and hyperuricaemia, not hypothyroidism.

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 Pharmacology question

What is the answer to this Pharmacology question?

The best answer is B, Ethionamide. Ethionamide, like para-aminosalicylic acid, can inhibit thyroid hormone synthesis and cause hypothyroidism, so thyroid function is monitored and levothyroxine given if needed.

Why is "Levofloxacin" not the answer?

Levofloxacin causes tendinopathy, QT prolongation and dysglycaemia.

Why is "Bedaquiline" not the answer?

Bedaquiline causes QT prolongation, nausea and hepatic enzyme rise.

Why is "Pyrazinamide" not the answer?

Pyrazinamide causes hepatotoxicity and hyperuricaemia, not hypothyroidism.

What concept does this question test?

It tests Antimicrobials: ethionamide hypothyroidism in Pharmacology. It also causes severe gastric intolerance and hepatitis. The other drugs have different toxicities.

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 Antimicrobials: ethionamide hypothyroidism?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology 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.