Complications of pregnancy: thyrotoxicosis in molar pregnancy: practice question

A OBG 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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OBG · Complications of pregnancy: thyrotoxicosis in molar pregnancy

Sample item

A woman with a complete hydatidiform mole has tachycardia, tremor and a suppressed TSH. What is the mechanism?

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

The answer and the reasoning

B. Very high hCG acts on the TSH receptor

hCG shares an alpha subunit with TSH and has weak TSH-like activity at very high levels, so it can stimulate the thyroid and suppress TSH. The thyrotoxicosis resolves after evacuation of the mole, and beta-blockers cover the acute phase.

Option by option

  • A. Thyroid autoantibodies are stimulating the gland

    Graves disease would be an autoimmune process unrelated to the mole.

  • B. Very high hCG acts on the TSH receptor (correct)

    Correct. The hCG level is high enough to stimulate the TSH receptor.

  • C. Excess iodine from placental tissue

    Iodine from placental tissue is not the cause.

  • D. A pituitary TSH-secreting adenoma

    A pituitary adenoma would not suppress TSH.

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 OBG question

What is the answer to this OBG question?

The best answer is B, Very high hCG acts on the TSH receptor. hCG shares an alpha subunit with TSH and has weak TSH-like activity at very high levels, so it can stimulate the thyroid and suppress TSH.

Why is "Thyroid autoantibodies are stimulating the gland" not the answer?

Graves disease would be an autoimmune process unrelated to the mole.

Why is "Excess iodine from placental tissue" not the answer?

Iodine from placental tissue is not the cause.

Why is "A pituitary TSH-secreting adenoma" not the answer?

A pituitary adenoma would not suppress TSH.

What concept does this question test?

It tests Complications of pregnancy: thyrotoxicosis in molar pregnancy in OBG. The thyrotoxicosis resolves after evacuation of the mole, and beta-blockers cover the acute phase.

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 Complications of pregnancy: thyrotoxicosis in molar pregnancy?

Learn management algorithms as steps: PPH, eclampsia, ectopic pregnancy. Then use the flashcards and the other OBG 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.