How is hyperaldosteronism diagnosed
What additional tests may be useful in identifying patients with hyperaldosteronism?
Many different tests have been proposed to distinguish between an aldosterone-producing adenoma and bilateral adrenal hyperplasia, including an assay of blood or urine for aldosterone (and/or other mineralocorticoids) before and after infusion of 2 L of saline, after a high-sodium diet, postural change, either an ACE inhibitor or an ARB, or an assay of serum 11- or 18-oxo-aldosterone. None of these are perfect discriminators, but the updated 2016 Endocrine Society guidelines suggest usually performing one of these confirmatory tests before imaging the adrenals. A CT scan of the abdomen, with thin (5 mm) cuts through the adrenals, is usually selected. If a unilateral hypodense mass >1 cm is found, particularly in a patient younger than 40 years, a surgeon is often consulted for laparoscopic removal (see later). Some physicians prefer a magnetic resonance imaging (MRI) scan, again with thin cuts through the adrenals, but this is less sensitive (because of the higher spatial resolution of CT scans).
Although challenged by the results of a randomized trial, adrenal venous sampling is recommended by the updated 2016 Endocrine Society guidelines for all surgical candidates over age 40 years, because CT scans have only 78% sensitivity and 75% specificity for unilateral adrenal adenomas. The procedure is complex and is typically done only at large, experienced centers, but it can help avoid removing an enlarged but nonfunctioning adrenal gland.
Glucocorticoid-remediable hyperaldosteronism can be detected by genetic testing of leukocyte DNA.