Angiotensin-responsive aldosterone-producing adenoma masquerades as idiopathic hyperaldosteronism (IHA: adrenal hyperplasia) or low-renin essential hypertension.

We have identified a subgroup of patients with aldosterone-producing adenoma (APA) who are responsive to angiotensin. Thus, a fall in plasma aldosterone (PA) during saline infusion may cause confusion with low-renin essential hypertension. Responsiveness of PA to angiotensin infusion and to upright posture may cause confusion with bilateral hyperplasia. Renin levels were not as completely suppressed in this angiotensin-responsive subgroup, leading to speculation that non-tumorous adrenal glomerulosa might also be less suppressed and might respond to angiotensin. This is unlikely, since angiotensin infusion soon after removal of the adenoma produced aldosterone levels of less than 10% of those achieved preoperatively. A biosynthetic peculiarity of the tumours is more likely, since urinary 18-oxo-cortisol levels were normal in this subgroup (as in bilateral hyperplasia) and raised in the more typical angiotensin-unresponsive subgroup (as in glucocorticoid-suppressible hyperaldosteronism). Since angiotensin-responsive tumours respond just as well to surgery as angiotensin-unresponsive tumours, it is important not to misdiagnose this subgroup as bilateral hyperplasia or low-renin essential hypertension.