Endocrine and Reproductive Systems Flashcards

A 45-year-old woman presents with weight gain, cold intolerance, constipation, and a TSH of 12 mIU/L with low free T4. Which is the most appropriate initial treatment?

Answer: Levothyroxine

Levothyroxine (synthetic T4) is the first-line treatment for hypothyroidism due to its stable half-life and reliable conversion to active T3.

On COMSAE, a patient with Cushing's syndrome undergoes an overnight dexamethasone suppression test. Which finding is most consistent with a pituitary ACTH-secreting adenoma (Cushing's disease)?

Answer: Suppression with high-dose dexamethasone

Pituitary Cushing's disease retains partial feedback sensitivity and suppresses cortisol with high-dose (but not low-dose) dexamethasone.

A 28-year-old woman has oligomenorrhea, hirsutism, and an LH:FSH ratio of 3:1. Pelvic ultrasound shows bilateral ovarian cysts. Which is the most likely diagnosis?

Answer: Polycystic ovary syndrome (PCOS)

PCOS is characterized by hyperandrogenism, oligoovulation, and polycystic ovaries, often with an elevated LH:FSH ratio.

A patient with type 2 diabetes has an HbA1c of 9.2% despite lifestyle modification. Which medication class improves insulin sensitivity primarily in peripheral tissues?

Answer: Thiazolidinediones

Thiazolidinediones (e.g., pioglitazone) activate PPAR-gamma receptors, enhancing insulin sensitivity in muscle and adipose tissue.

Which hormone is primarily responsible for stimulating milk ejection (let-down reflex) during breastfeeding?

Answer: Oxytocin

Oxytocin, released from the posterior pituitary in response to suckling, causes myoepithelial cell contraction and milk ejection.

A 32-year-old man presents with bilateral gynecomastia, small firm testes, and infertility. Karyotype shows 47,XXY. Which of the following best describes this condition?

Answer: Klinefelter syndrome

Klinefelter syndrome (47,XXY) presents with hypogonadism, infertility, gynecomastia, and small firm testes due to seminiferous tubule dysgenesis.