Endocrine System MCAT Practice Question
A patient with primary hyperaldosteronism (aldosterone-secreting adrenal adenoma) shows elevated plasma aldosterone, suppressed plasma renin activity, and hypertension. When the patient receives a saline loading test (high sodium intake), aldosterone levels fail to suppress appropriately. Which of the following best explains this autonomous hormone secretion?
Answer choices
- AThe adenoma retains responsiveness to angiotensin II but becomes insensitive to sodium-mediated renin suppression
- BThe adenoma secretes aldosterone autonomously, independent of normal regulatory signals including renin and angiotensin IICorrect answer
- CHigh sodium intake paradoxically stimulates aldosterone secretion through direct effects on adrenocortical cells
- DThe adenoma produces ectopic renin, maintaining angiotensin II levels despite suppressed juxtaglomerular renin
- ESodium loading increases sympathetic nervous system activity, which stimulates aldosterone secretion from the adenoma
- FThe adenoma has developed constitutive activation of the renin-angiotensin-aldosterone system pathway due to mutations in negative feedback regulators
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