Noninvasive adrenal imaging in hyperaldosteronism: is it accurate for correctly identifying patients who should be selected for surgery?

BACKGROUND AND AIMS: The most common causes of hyperaldosteronism (HA) are bilateral idiopathic hyperaldosteronism (IHA), aldosterone-producing adenoma (APA), and unilateral primary adrenal hyperplasia (PAH). We evaluated if non-invasive preoperative imaging studies are able to reliably differentiate these causes of hyperaldosteronism. METHODS: The medical records of 50 consecutive patients with HA were reviewed. Follow up was obtained by outpatient consultation or phone contact. RESULTS: Thirty-five patients (70%) underwent successful adrenalectomy for APA, basing on the computed tomography (CT) scan results only. All these patients were biochemically cured. The remaining 15 patients underwent dexamethasone suppression adrenal cortical scintiscan (ACS) because of equivocal or inconclusive CT scan. In 11 of these patients, ACS showed a bilateral uptake, suggesting IHA. They were followed-up. In the remaining four patients, ACS showed a unilateral uptake. These patients underwent adrenalectomy. Final histology showed APA in three patients and PAH in one. They were biochemically cured. Sensitivity of combined non-invasive imaging procedures (CT and ACS) in detecting histologically proven and biochemically cured APA and PAH was 100%. CONCLUSION: Non-invasive adrenal imaging studies are accurate in distinguishing between IHA and APA/PAH. Invasive diagnostic tests (adrenal venous sampling) should be indicated only when they do not conclusively localize hypersecretion.