Primary aldosteronism: adrenal venous sampling

In primary aldosteronism, high-resolution adrenal computed tomography (CT) increasingly identifies subtle anatomic abnormalities. To interpret the functional significance of adrenal micronodular changes on CT scan, we have reevaluated selective adrenal venous sampling.

Thirty-four patients with primary aldosteronism were selected prospectively for adrenal venous sampling on the basis of CT findings: normal findings or minimal thickening of an adrenal limb (n = 15), unilateral microadenoma (n = 6), bilateral adrenal nodules (n = 9), or atypical unilateral adrenal macroadenoma (n = 4).

Both adrenal veins were catheterized in 33 of 34 patients. Six (40%) of 15 patients with normal or minimal adrenal limb thickening had a unilateral source of aldosterone. Six patients with apparent unilateral microadenoma had ipsilateral aldosterone-producing adenomas. Four (44%) of nine patients with bilateral adrenal masses had a unilateral source of aldosterone secretion. Three of four patients with unilateral atypical adrenal macroadenomas had ipsilateral aldosterone-producing adenomas.

A unilateral source of aldosterone excess may be found in selected patients with adrenal glands that appear normal or show a minimally expanded adrenal limb on CT scan. Findings on adrenal venous sampling are crucial in determining the source of aldosterone excess in patients with bilateral adrenal masses or atypical-appearing macroadenomas.