Endocrine physiology: thyroid: practice question

A Physiology 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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Physiology · Endocrine physiology: thyroid

Sample item

A patient with thyrotoxicosis is given a large dose of iodide before surgery, and thyroid hormone synthesis and release fall transiently. What is this effect called?

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

The answer and the reasoning

A. Wolff-Chaikoff effect

A large iodide load temporarily inhibits thyroid peroxidase-mediated organification and hormone release, the Wolff-Chaikoff effect. The block lasts days and is the basis of pre-operative Lugol iodine use. Escape from the effect can occur with continued exposure.

Option by option

  • A. Wolff-Chaikoff effect (correct)

    Correct. High intrathyroidal iodide inhibits hormone synthesis.

  • B. Jod-Basedow effect

    The Jod-Basedow effect is iodine-induced hyperthyroidism in an autonomous gland.

  • C. Pendred effect

    Pendred syndrome is a defect of iodide organification with deafness, not a physiological effect.

  • D. Plummer effect

    Plummer disease is toxic nodular goitre, not an iodide effect.

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 Physiology question

What is the answer to this Physiology question?

The best answer is A, Wolff-Chaikoff effect. A large iodide load temporarily inhibits thyroid peroxidase-mediated organification and hormone release, the Wolff-Chaikoff effect.

Why is "Jod-Basedow effect" not the answer?

The Jod-Basedow effect is iodine-induced hyperthyroidism in an autonomous gland.

Why is "Pendred effect" not the answer?

Pendred syndrome is a defect of iodide organification with deafness, not a physiological effect.

Why is "Plummer effect" not the answer?

Plummer disease is toxic nodular goitre, not an iodide effect.

What concept does this question test?

It tests Endocrine physiology: thyroid in Physiology. The block lasts days and is the basis of pre-operative Lugol iodine use. Escape from the effect can occur with continued exposure.

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 Endocrine physiology: thyroid?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.