Endocrinology: Graves disease in pregnancy: 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: Graves disease in pregnancy

Sample item

A woman with Graves disease on carbimazole finds she is 6 weeks pregnant. Her free T4 is raised. What is the most appropriate change in management during the first trimester?

AImmediate total thyroidectomyBSwitch to propylthiouracilCGive radioactive iodineDContinue carbimazole at the same dose

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

The answer and the reasoning

B. Switch to propylthiouracil

Carbimazole and methimazole are associated with an embryopathy (aplasia cutis, choanal atresia and oesophageal atresia) when used in early pregnancy, so propylthiouracil is preferred in the first trimester. Because of PTU hepatotoxicity, many switch back to methimazole after the first trimester. Radioiodine is contraindicated in pregnancy and the lowest effective dose of antithyroid drug is used.

Option by option

A. Immediate total thyroidectomy
Surgery is reserved for failure of drug therapy and, if needed, is done in the second trimester.
B. Switch to propylthiouracil (correct)
PTU is the preferred antithyroid drug in the first trimester because of the lower teratogenic risk.
C. Give radioactive iodine
Radioiodine crosses the placenta and would ablate the foetal thyroid.
D. Continue carbimazole at the same dose
Carbimazole during organogenesis carries a risk of congenital malformations.

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.

Questions about this General Medicine question

What is the answer to this General Medicine question?

The best answer is B, Switch to propylthiouracil. Carbimazole and methimazole are associated with an embryopathy (aplasia cutis, choanal atresia and oesophageal atresia) when used in early pregnancy, so propylthiouracil is preferred in the first trimester.

Why is "Immediate total thyroidectomy" not the answer?

Surgery is reserved for failure of drug therapy and, if needed, is done in the second trimester.

Why is "Give radioactive iodine" not the answer?

Radioiodine crosses the placenta and would ablate the foetal thyroid.

Why is "Continue carbimazole at the same dose" not the answer?

Carbimazole during organogenesis carries a risk of congenital malformations.

What concept does this question test?

It tests Endocrinology: Graves disease in pregnancy in General Medicine. Because of PTU hepatotoxicity, many switch back to methimazole after the first trimester. Radioiodine is contraindicated in pregnancy and the lowest effective dose of antithyroid drug is used.

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 Endocrinology: Graves disease in pregnancy?

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.