USMLE PRACTICE QUESTION #92
TOPIC: Reproductive Pharmacology
Today’s question will test your understanding of a commonly tested reproductive pharmacology question.
I’m Paul Ciurysek, MD, founder of The USMLE Guys, and this is The USMLE Times. This daily newsletter aims to provide you with super high-yield USMLE concepts that are commonly tested on exam day. All content is FREE! If you’d like to work with me and my team, please see the options at the bottom of today’s newsletter. If you’d like to support my efforts, please share the newsletter with a friend.
A 32-year-old woman presents to her primary care physician with complaints of difficulty conceiving for the past year, despite having regular unprotected intercourse. She has regular menstrual cycles and no significant medical history. Her vital signs are as follows: Blood pressure 118/72 mmHg, pulse 72 beats/minute, respiratory rate 16 breaths/minute, and temperature 98.4°F (36.9°C). After discussing various options with her physician, she is prescribed a trial of clomiphene. Which of the following best describes clomiphene’s mechanism of action in fertility treatment?
A) Direct stimulation of the ovaries to increase follicle production
B) Stimulation of estrogen receptors in the hypothalamus
C) Increased FSH and LH secretion from the pituitary gland
D) Suppression of progesterone synthesis by the corpus luteum
E) Increased GnRH secretion by the pituitary gland
F) Induction of ovulation through increased production of estrogen
G) Inhibition of androgen receptors in the ovaries
Detailed Breakdown of Answers + Correct Answer Below ⏬
ANSWER + QUESTION BREAKDOWN
The MENTAL MODEL used to answer this question comes from our detailed test-taking skills masterclass (check it out if you want to elevate your skills). Here’s how to think through this question:
Step 1. Read the last line to get to the heart of the question: “Which of the following best describes clomiphene’s mechanism of action in fertility treatment?”
Step 2: Is this a first-, second-, or third-order question?
Answer: 1st order. 1st: Identify the MOA of clomiphene.
Step 3: Read the vignette carefully and ask yourself: “How does clomiphene work in the context of the vignette?”
Step 4. Look at the answer choices and select the option most closely resembling your final thought from “Step 3” above.
GENERAL ANALYSIS
The 32-year-old woman is being treated with clomiphene to address her difficulty conceiving. Clomiphene is a selective estrogen receptor modulator, and its mechanism of action involves increasing the release of gonadotropins, which stimulates ovulation.
ANSWER CHOICES:
CHOICE A: Direct stimulation of the ovaries to increase follicle production
Explanation: This would describe treatments like exogenous FSH administration, which directly stimulates the ovaries. Clomiphene does not directly stimulate the ovaries but works by increasing FSH and LH levels via its action on the hypothalamus and pituitary.
CHOICE B: Stimulation of estrogen receptors in the hypothalamus
Explanation: This option suggests that clomiphene acts as an estrogen agonist in the hypothalamus. Clomiphene acts as an estrogen antagonist in the hypothalamus, blocking estrogen receptors to increase GnRH secretion.
CHOICE C: Increased FSH and LH secretion from the pituitary gland
Explanation: Clomiphene works by blocking estrogen receptors in the hypothalamus, which interferes with the normal negative feedback mechanism of estrogen. The hypothalamus perceives low estrogen levels and responds by increasing gonadotropin-releasing hormone release. This increase in GnRH stimulates the pituitary gland to secrete more follicle-stimulating hormone and luteinizing hormone, which promote follicular development and ovulation in the ovaries.
CHOICE D: Suppression of progesterone synthesis by the corpus luteum
Explanation: Progesterone is produced by the corpus luteum after ovulation. Clomiphene does not suppress progesterone synthesis; rather, it promotes ovulation, after which normal progesterone production occurs.
CHOICE E: Increased GnRH secretion by the pituitary gland
Explanation: GnRH is secreted by the hypothalamus, not the pituitary gland; making this option factually impossible.
CHOICE F: Induction of ovulation through increased production of estrogen
Explanation: Estrogen levels rise as a result of follicle development, but clomiphene’s primary action is to block estrogen receptors in the hypothalamus. Clomiphene induces ovulation by increasing FSH and LH levels, not by directly increasing estrogen production.
CHOICE G: Inhibition of androgen receptors in the ovaries
Explanation: This would describe drugs that block androgen activity. Clomiphene does not act on androgen receptors; its mechanism involves estrogen receptor modulation.
FINAL VERDICT…
Clomiphene increases fertility by blocking estrogen receptors in the hypothalamus, leading to increased secretion of FSH and LH from the pituitary gland, which stimulates ovulation.
CORRECT ANSWER: C) Increased FSH and LH secretion from the pituitary gland
1) 1-ON-1 STEP 1 COACHING: If you’re looking for a personalized approach and guidance designed for your specific needs, goals, and challenges, then 1-on-1 coaching might be what you’re looking for. Choose between daily sessions with Dr. Paul for four, six, or eight weeks. CLICK HERE TO LEARN MORE ABOUT 1-ON-1 COACHING.
2) 1-ON-1 STRATEGY SESSION: If you need some guidance or a plan to get to where you’re going, join me for a 1-on-1 strategy session. This will help you clarify a plan, identify and overcome potential challenges, and give you the best chance for a smooth ride from where you are now to where you’re going. These are done 1-on-1 with me (Dr. Paul), so space is limited. SET UP YOUR 1-ON-1 STRATEGY SESSION HERE
3) THE MASTER CLASSES: I've created two masterclasses based around two of the most commonly experienced challenges I've helped students overcome in the last 15+ years: Test-taking skills and How to get into Residency. These will give you the knowledge, skills, and tools to crush your USMLE exams and match into your dream Residency program. LEARN ABOUT THE MASTERCLASSES HERE
4) ASSESSMENT EXAMS: Save those valuable NBME assessments! Our assessment exam platform was designed to help you identify your strengths, weaknesses, and exam readiness without prematurely wasting your NBME exams. With our USMLEDx assessment platform, you can assess yourself early and often while saving those highly valuable NBMEs for the final stretch of your exam prep. CHECK OUT THE ASSESSMENT EXAM OPTIONS HERE
That’s it for question 92!
See ya tomorrow 👋