Endocrinology and diabetes: iodine-induced hyperthyroidism: 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 · Endocrinology and diabetes: iodine-induced hyperthyroidism

Sample item

A woman from an iodine-deficient hilly region has a long-standing multinodular goitre. She develops palpitations and weight loss within weeks of receiving iodinated contrast for a CT scan. What is the mechanism?

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

The answer and the reasoning

A. Autonomous nodules make excess hormone when given an iodine load

Iodine-induced hyperthyroidism (Jod-Basedow phenomenon) occurs when iodine is given to patients with nodular goitres with autonomous function, often after deficiency. In contrast, the Wolff-Chaikoff effect is the transient inhibition of hormone synthesis by excess iodine, which can cause hypothyroidism.

Option by option

  • A. Autonomous nodules make excess hormone when given an iodine load (correct)

    Correct. Autonomous nodules use the iodine supply to produce hormone without TSH control.

  • B. Destruction of follicles with release of stored hormone

    Follicle destruction causes thyroiditis with a low radioiodine uptake and a painful or painless course.

  • C. Stimulation of the TSH receptor by autoantibodies

    Receptor-stimulating antibodies cause Graves disease, which is not triggered by contrast in a nodular goitre.

  • D. Acute inhibition of thyroid hormone organification by excess iodine

    Inhibition of organification is the Wolff-Chaikoff effect, which lowers hormone production.

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 A, Autonomous nodules make excess hormone when given an iodine load. Iodine-induced hyperthyroidism (Jod-Basedow phenomenon) occurs when iodine is given to patients with nodular goitres with autonomous function, often after deficiency.

Why is "Destruction of follicles with release of stored hormone" not the answer?

Follicle destruction causes thyroiditis with a low radioiodine uptake and a painful or painless course.

Why is "Stimulation of the TSH receptor by autoantibodies" not the answer?

Receptor-stimulating antibodies cause Graves disease, which is not triggered by contrast in a nodular goitre.

Why is "Acute inhibition of thyroid hormone organification by excess iodine" not the answer?

Inhibition of organification is the Wolff-Chaikoff effect, which lowers hormone production.

What concept does this question test?

It tests Endocrinology and diabetes: iodine-induced hyperthyroidism in General Medicine. In contrast, the Wolff-Chaikoff effect is the transient inhibition of hormone synthesis by excess iodine, which can cause hypothyroidism.

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 Endocrinology and diabetes: iodine-induced hyperthyroidism?

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.