Endocrine Weight Loss Endocrine Pathology 5 — Questions and Answers
Question 1: Prader-Willi syndrome causes obesity through which primary endocrine/neurological mechanism?
- Hypothyroid state from thyroid aplasia
- Hypothalamic dysfunction causing insatiable hunger (hyperphagia) and GH deficiency (Correct answer)
- Adrenal cortisol excess from bilateral hyperplasia
- Pancreatic glucagonoma with reactive insulin surge
Correct answer: Hypothalamic dysfunction causing insatiable hunger (hyperphagia) and GH deficiency
Prader-Willi syndrome involves hypothalamic dysfunction resulting in hyperphagia, GH deficiency, hypogonadism, and severe early-childhood obesity.
Question 2: A patient on long-term glucocorticoid therapy for rheumatoid arthritis develops weight gain, striae, and hyperglycemia. This iatrogenic condition mimics which endocrine disease?
- Addison's disease
- Cushing's syndrome (Correct answer)
- Graves' disease
- Primary hyperaldosteronism
Correct answer: Cushing's syndrome
Long-term exogenous glucocorticoid use produces iatrogenic Cushing's syndrome with the same features as endogenous cortisol excess.
Question 3: In non-alcoholic fatty liver disease (NAFLD) associated with obesity, which endocrine abnormality most directly drives hepatic fat accumulation?
- Growth hormone deficiency reducing lipolysis
- Hyperinsulinemia stimulating de novo lipogenesis in the liver (Correct answer)
- Elevated glucagon promoting hepatic glucose uptake
- Low adiponectin reducing hepatic fat oxidation independently of insulin
Correct answer: Hyperinsulinemia stimulating de novo lipogenesis in the liver
Hyperinsulinemia from insulin resistance stimulates SREBP-1c–driven de novo lipogenesis in the liver, a key driver of NAFLD.
Question 4: Which imaging modality is the gold standard for quantifying visceral adipose tissue (VAT) in research and clinical metabolic risk assessment?
- Dual-energy X-ray absorptiometry (DEXA)
- Abdominal CT scan at the L4-L5 level (Correct answer)
- Ultrasound of the abdomen
- MRI of the thorax
Correct answer: Abdominal CT scan at the L4-L5 level
CT cross-sectional area at L4-L5 is the gold standard for measuring visceral fat volume, distinguishing VAT from subcutaneous fat.
Question 5: A man with hypogonadism (low testosterone) presents with increased body fat and loss of muscle mass. Testosterone replacement therapy is expected to:
- Increase fat mass and decrease lean mass further
- Reduce visceral fat and increase lean body mass (Correct answer)
- Have no effect on body composition
- Increase water retention causing apparent weight gain only
Correct answer: Reduce visceral fat and increase lean body mass
Testosterone promotes muscle protein synthesis and lipolysis; replacing deficient testosterone in hypogonadal men reduces fat mass and increases lean mass.
Question 6: Which peptide hormone, co-secreted with insulin from pancreatic beta cells, is deficient in type 2 diabetes and, when replaced, reduces food intake and glucagon secretion?
- Somatostatin
- Amylin (pramlintide) (Correct answer)
- Pancreatic polypeptide
- Vasoactive intestinal peptide
Correct answer: Amylin (pramlintide)
Amylin is co-secreted with insulin and suppresses glucagon, slows gastric emptying, and promotes satiety; pramlintide is its synthetic replacement used in diabetes.
Question 7: Brown adipose tissue (BAT) contributes to energy expenditure through which unique mechanism not found in white adipose tissue?
- Storing triglycerides for future energy use
- Non-shivering thermogenesis via uncoupling protein-1 (UCP-1) (Correct answer)
- Secreting leptin to suppress appetite centrally
- Converting excess glucose to glycogen
Correct answer: Non-shivering thermogenesis via uncoupling protein-1 (UCP-1)
BAT expresses UCP-1, which uncouples the mitochondrial proton gradient from ATP synthesis, dissipating energy as heat instead of storing it.
Endocrine Weight Loss Endocrine Pathology 5
Prader-Willi syndrome causes obesity through which primary endocrine/neurological mechanism?