Gynaecological endocrinology: GnRH pulsatility: 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 · Gynaecological endocrinology: GnRH pulsatility

Sample item

Why does continuous administration of a GnRH agonist suppress ovarian function, while pulsatile administration stimulates it?

APulsatile dosing destroys pituitary cellsBGnRH agonists act only on the hypothalamusCContinuous administration blocks the ovary directlyDContinuous stimulation desensitises and downregulates pituitary GnRH receptors

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

The answer and the reasoning

D. Continuous stimulation desensitises and downregulates pituitary GnRH receptors

The pituitary gonadotrophs need pulsatile GnRH exposure, about one pulse every 60 to 90 minutes, to release FSH and LH. Continuous agonist exposure causes an initial flare and then receptor downregulation and a hypo-oestrogenic state, which is used in endometriosis, fibroids and central precocious puberty. Pulsatile pumps are used to induce ovulation in hypothalamic amenorrhoea.

Option by option

A. Pulsatile dosing destroys pituitary cells
Pulsatile dosing mimics physiology and does not destroy cells.
B. GnRH agonists act only on the hypothalamus
The agonists act on pituitary GnRH receptors.
C. Continuous administration blocks the ovary directly
The suppression is at the pituitary level and not a direct ovarian block.
D. Continuous stimulation desensitises and downregulates pituitary GnRH receptors (correct)
Correct. Continuous exposure downregulates pituitary receptors, causing suppression.

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 OBG question

What is the answer to this OBG question?

The best answer is D, Continuous stimulation desensitises and downregulates pituitary GnRH receptors. The pituitary gonadotrophs need pulsatile GnRH exposure, about one pulse every 60 to 90 minutes, to release FSH and LH.

Why is "Pulsatile dosing destroys pituitary cells" not the answer?

Pulsatile dosing mimics physiology and does not destroy cells.

Why is "GnRH agonists act only on the hypothalamus" not the answer?

The agonists act on pituitary GnRH receptors.

Why is "Continuous administration blocks the ovary directly" not the answer?

The suppression is at the pituitary level and not a direct ovarian block.

What concept does this question test?

It tests Gynaecological endocrinology: GnRH pulsatility in OBG. Continuous agonist exposure causes an initial flare and then receptor downregulation and a hypo-oestrogenic state, which is used in endometriosis, fibroids and central precocious puberty. Pulsatile pumps are used to induce ovulation in hypothalamic amenorrhoea.

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 Gynaecological endocrinology: GnRH pulsatility?

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.