A 48-year-old man had a 7-year history of hypertension that was not optimally controlled on four antihypertensive drugs (β-adrenergic blocker, peripheral α1-antagonist, angiotensin receptor blocker, and a thiazide diuretic). He was not hypokalemic. Resistant hypertension prompted case-detection testing for primary aldosteronism with a plasma aldosterone concentration (PAC) of 15 ng/dL and low plasma renin activity (PRA) at less than 0.6 ng/mL/h (PAC-PRA ratio > 25). The confirmatory test for primary aldosteronism was also positive, with 24-hour urinary excretion of aldosterone of 16 μg on a high-sodium diet (urinary sodium, 356 mEq/24 h). A. Adrenal CT split section axial images show a 12-mm thickening (large arrow) in the inferior aspect of the left adrenal gland and a tiny nodule (small arrow) in the right adrenal gland. The patient wanted to pursue a surgical approach to the resolution of or improvement in hypertension. B. Adrenal venous sampling images showing the catheter in the right and left adrenal veins. The delicate venous architecture is demonstrated. C. Adrenal venous sampling lateralized aldosterone secretion to the right adrenal gland, and a 3-mm yellow cortical adenoma was found at laparoscopic right adrenalectomy. The postoperative plasma aldosterone concentration was less than 1.0 ng/dL. One year after surgery, his blood pressure was in the normal range with the aid of one antihypertensive medication. (Reproduced with permission from: Young WF. Endocrine Hypertension: Then and Now. Endocr Pract. 2010;16:888-902.) Source: Chapter 10. Endocrine Hypertension, Greenspan’s Basic & Clinical Endocrinology, 9e Citation: Gardner DG, Shoback D. Greenspan’s Basic & Clinical Endocrinology, 9e; 2011 Available at: http://accessmedicine.mhmedical.com/DownloadImage.aspx?image=/data/books/gard9/gard9_c010f008a.jpg&sec=39747056&BookID=380&ChapterSecID=39744050&imagename= Accessed: November 10, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved