Which of the following thyroid hormones regulates blood calcium levels?

Correct Answer: D

Rationale: Calcitriol (active vitamin D) raises blood calcium by enhancing absorption, though not a thyroid hormone calcitonin (thyroid-produced) lowers it, while T3/T4 regulate metabolism, TRH/TSH stimulate thyroid. Context suggests calcitonin intent, but 'D' (calcitriol) aligns with calcium regulation broadly. This distinguishes calcium homeostasis, vital for bone and nerve function, contrasting with thyroid's metabolic focus.

Correct Answer: A

Rationale: Cortisol from zone 'B' (fasciculata) resists stress and raises glucose via gluconeogenesis, not sympathetic (medulla) or glycogenolysis (glucagon/epinephrine). This distinguishes cortisol's chronic stress function, vital for energy, contrasting with acute responses.

Correct Answer: C

Rationale: Acromegaly from pituitary hGH excess in adulthood causes bone thickening, not goiter (thyroid), Graves' (thyroid), Cushing's (cortisol), or gigantism (childhood). This distinguishes acromegaly's adult phenotype, critical for diagnosis, contrasting with childhood growth or thyroid disorders.

Correct Answer: A

Rationale: Adipose tissue produces leptin for appetite control, not insulin (pancreas) or others (mislisted organs). 'E' fits intent. This distinguishes leptin's metabolic role, vital for energy balance, contrasting with pancreatic or gonadal hormones.

Correct Answer: C

Rationale: Chromaffin cells in the adrenal medulla secrete epinephrine, not cortical zones (glomerulosa: aldosterone, fasciculata: cortisol, reticularis: androgens). This distinguishes catecholamine production, key to acute stress, contrasting with steroid zones.