Pheochromocytoma and Aldosterone Excess

Pathophysiology and Relationship

Primary aldosteronism is a condition caused by autonomous aldosterone production, typically from an aldosterone-producing adenoma or bilateral adrenal hyperplasia, as stated by the American Heart Association 1, 2
These conditions are distinct entities with different cellular origins - pheochromocytoma arises from the adrenal medulla while aldosterone-producing tumors arise from the adrenal cortex, according to the American Urological Association 3

When evaluating patients with suspected adrenal tumors, comprehensive hormonal evaluation is recommended, including testing for both catecholamine excess and aldosterone excess, as suggested by the Endocrine Society 4
All patients with adrenal masses should undergo screening for autonomous cortisol secretion, and those with hypertension and/or hypokalemia should be screened for primary aldosteronism with an aldosterone-to-renin ratio, as recommended by the American Urological Association 3
Patients with adrenal masses >10 HU on non-contrast CT or with signs/symptoms of catecholamine excess should be screened for pheochromocytoma with plasma or 24-hour urinary metanephrines, according to the Endocrine Society 3, 5

Plasma free metanephrines is the most sensitive and specific test for diagnosing pheochromocytoma, as stated by the Endocrine Society 5
Aldosterone-to-renin ratio is the preferred screening test for primary aldosteronism in patients with hypertension and/or hypokalemia, according to the American Urological Association 3
If both conditions are suspected, both sets of tests should be performed, as the presence of one does not exclude the other, as suggested by the Endocrine Society 4

Relying solely on radiological appearance to predict hormone secretion status is unreliable - functional testing is essential, as warned by the Endocrine Society 4
Never perform adrenal biopsy without excluding pheochromocytoma first, as this can trigger life-threatening hypertensive crisis, according to the Endocrine Society 4, 5
Hypokalemia is a late manifestation of primary aldosteronism, so normal potassium levels do not exclude the diagnosis, as noted by the American Heart Association 1, 2