Endocrine Weight Loss Sex Hormones and Body Composition 2 — Questions and Answers
Question 1: In polycystic ovary syndrome (PCOS), elevated androgens contribute to weight gain primarily by promoting:
- Subcutaneous gluteal fat accumulation
- Visceral and abdominal fat accumulation (Correct answer)
- Reduced appetite and caloric intake
- Increased thyroid hormone production
Correct answer: Visceral and abdominal fat accumulation
Elevated androgens in PCOS promote visceral and abdominal fat accumulation, which further worsens insulin resistance and creates a cycle that perpetuates weight gain.
Question 2: Sex hormone-binding globulin (SHBG) levels are typically reduced in obesity. What is the clinical consequence of low SHBG?
- More testosterone and estrogen are protein-bound and inactive
- More free (bioavailable) sex hormones are available to tissues (Correct answer)
- Androgen deficiency symptoms occur despite normal total testosterone
- SHBG reduction has no clinical significance
Correct answer: More free (bioavailable) sex hormones are available to tissues
Low SHBG means less sex hormone is protein-bound, increasing the free bioavailable fraction of testosterone and estrogen, which can amplify androgenic or estrogenic effects in tissues.
Question 3: Adipose tissue expresses aromatase enzyme. What does this mean for obese postmenopausal women?
- They produce less estrogen than lean postmenopausal women
- Peripheral conversion of androgens to estrogen increases with greater fat mass (Correct answer)
- Adipose aromatase converts estrogen to androgens
- Aromatase activity in fat tissue is clinically irrelevant
Correct answer: Peripheral conversion of androgens to estrogen increases with greater fat mass
Aromatase in adipose tissue converts androgens (such as androstenedione) to estrogens, so obese postmenopausal women have higher peripheral estrogen levels than lean postmenopausal women despite absent ovarian production.
Question 4: Which mechanism best explains why men with hypogonadism often develop insulin resistance and central obesity?
- Low testosterone increases SHBG, sequestering insulin
- Testosterone deficiency reduces muscle mass, lowering glucose uptake and metabolic rate (Correct answer)
- Low testosterone stimulates cortisol production, causing hyperglycemia
- Hypogonadism directly inhibits pancreatic beta cell function
Correct answer: Testosterone deficiency reduces muscle mass, lowering glucose uptake and metabolic rate
Testosterone is essential for maintaining muscle mass; deficiency causes sarcopenia (muscle loss), which reduces the major site of glucose disposal, leading to insulin resistance and preferential fat accumulation.
Question 5: A woman with PCOS is found to have elevated free testosterone and insulin resistance. Which treatment approach addresses both problems simultaneously?
- Testosterone replacement therapy
- Metformin, which reduces insulin resistance and thereby lowers androgen production (Correct answer)
- High-dose estrogen therapy
- Thyroid hormone supplementation
Correct answer: Metformin, which reduces insulin resistance and thereby lowers androgen production
Metformin reduces insulin resistance, which lowers insulin-driven stimulation of ovarian androgen production, addressing both hyperinsulinemia and hyperandrogenism simultaneously in PCOS.
Question 6: Estradiol (E2) is the predominant estrogen in premenopausal women, while estrone (E1) predominates postmenopausally. How does this shift affect weight?
- Estrone is more potent than estradiol, promoting greater fat loss
- Estrone is a weaker estrogen, providing less protection against visceral fat accumulation (Correct answer)
- Estrone preferentially promotes subcutaneous fat storage like estradiol
- The shift between estrogen types has no effect on body weight
Correct answer: Estrone is a weaker estrogen, providing less protection against visceral fat accumulation
Estrone is a weaker estrogen than estradiol, so the postmenopausal shift to estrone-dominant estrogen status provides less protection against visceral fat accumulation and metabolic dysfunction.
Question 7: In men, excess adipose tissue (obesity) can lead to decreased testosterone levels through which primary mechanism?
- Fat cells secrete testosterone antagonists that block androgen receptors
- Adipose aromatase converts testosterone to estradiol, reducing circulating testosterone (Correct answer)
- Obesity stimulates SHBG production, which binds all available testosterone
- Excess fat increases LH pulsatility, suppressing testicular function
Correct answer: Adipose aromatase converts testosterone to estradiol, reducing circulating testosterone
Aromatase in excess adipose tissue converts testosterone to estradiol, reducing circulating testosterone levels while elevating estrogen, which further suppresses the HPG axis through negative feedback.
Endocrine Weight Loss Sex Hormones and Body Composition 2
In polycystic ovary syndrome (PCOS), elevated androgens contribute to weight gain primarily by promoting: