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Reproductive & Endocrine Physiology — Step 1 practice questions
94 questions in this area, with an explanation for every answer choice.
Three samples below, free and without an account.
How this shows up on Step 1
Physiology questions in this section combine two things the exam tests separately elsewhere. Physiology questions can be reasoned rather than recalled, which makes them the best return on study time. Endocrine questions are built on feedback loops.
Sample questions
Sample question 1
A 22-year-old woman has goiter, tachycardia, and elevated free T4 and T3, but her TSH is INAPPROPRIATELY normal rather than suppressed. There is no evidence of a pituitary mass and her father has similar laboratory findings. Which of the following best explains these results?
Explanations
A. Graves disease with thyroid-stimulating immunoglobulins
Graves disease suppresses TSH profoundly.
B. Iodine-induced hyperthyroidism
Iodine-induced hyperthyroidism (Jod-Basedow) likewise suppresses TSH.
C. Subacute thyroiditis with hormone leak
Thyroiditis suppresses TSH and shows low radioiodine uptake with a painful gland.
D. Factitious thyroid hormone ingestion
Exogenous hormone also suppresses TSH, and causes a SMALL thyroid with low thyroglobulin.
E. A mutation in the thyroid hormone receptor beta gene causing tissue resistance to thyroid hormone · correct
Resistance to thyroid hormone (usually a dominant THRB mutation) blunts negative feedback at the pituitary, so TSH is not suppressed despite high free hormone levels. Tissues expressing predominantly TR-beta (pituitary, liver) are resistant, while TR-alpha-rich tissues (heart) may show thyrotoxic features — producing the mixed picture of goiter and tachycardia with a "non-suppressed TSH." The family history supports an inherited defect; a TSH-secreting pituitary adenoma is the main differential.
Sample question 2
Which of the following hormones directly stimulates Leydig cells to produce testosterone?
Explanations
A. LH · correct
LH directly stimulates Leydig cells to produce testosterone, analogous to LH's role stimulating theca cell androgen production in females.
B. Prolactin
Prolactin is not the stimulus for Leydig cell function; in excess, it can actually suppress the reproductive axis.
C. FSH
FSH primarily acts on Sertoli cells (supporting spermatogenesis and inhibin production), not directly stimulating Leydig cell testosterone production.
D. Inhibin
Inhibin, produced by Sertoli cells, provides negative feedback on FSH, not a stimulatory hormone for Leydig cells.
E. Estrogen
Estrogen is not the stimulus for Leydig cell testosterone production (though some testosterone is peripherally aromatized to estrogen).
Sample question 3
A couple has been unable to conceive after 12 months of regular unprotected intercourse. Which of the following best describes the appropriate initial evaluation?
Explanations
A. Evaluate only if the woman has irregular cycles
Regular cycles do not exclude infertility from tubal or male factors.
B. Wait an additional 2 years before any evaluation
Delay reduces success, particularly with advancing maternal age.
C. Evaluate BOTH partners simultaneously — semen analysis for the man, and assessment of ovulation, tubal patency, and ovarian reserve for the woman · correct
Infertility is defined as failure to conceive after 12 months of unprotected intercourse, or 6 months if the woman is over 35. Because a MALE factor contributes in roughly 40–50% of cases, both partners are evaluated SIMULTANEOUSLY — semen analysis is inexpensive and noninvasive, and evaluating it first avoids subjecting the woman to unnecessary invasive testing. Female evaluation assesses ovulation (cycle history, mid-luteal progesterone), tubal patency (hysterosalpingography), and ovarian reserve.
D. Proceed directly to in vitro fertilization without evaluation
Treatment should follow identification of the cause.
E. Evaluate the female partner first and the male only if she is normal
Sequential evaluation delays diagnosis and burdens the female partner unnecessarily.
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