Diagnosis and management of primary aldosteronism

Abstract

Primary aldosteronism (PA) is the most common form of secondary hypertension (HTN), with an estimated prevalence of 4% of hypertensive patients in primary care and around 10% of referred patients. Patients with PA have higher cardiovascular morbidity and mortality than age- and sex-matched patients with essential HTN and the same degree of blood pressure elevation. PA is characterized by an autonomous aldosterone production causing sodium retention, plasma renin supression, HTN, cardiovascular damage, and increased potassium excretion, leading to variable degrees of hypokalemia. Aldosterone-producing adenomas (APAs) account for around 40% and idiopathic hyperaldosteronism for around 60% of PA cases. The aldosterone-to-renin ratio is the most sensitive screening test for PA. There are several confirmatory tests and the current literature does not identify a "gold standard" confirmatory test for PA. In our institution, we recommend starting case confirmation with the furosemide test. After case confirmation, all patients with PA should undergo adrenal CT as the initial study in subtype testing to exclude adrenocortical carcinoma. Bilateral adrenal vein sampling (AVS) is the gold standard method to define the PA subtype, but it is not indicated in all cases. An experienced radiologist must perform AVS. Unilateral laparoscopic adrenalectomy is the preferential treatment for patients with APAs, and bilateral hyperplasia should be treated with mineralocorticoid antagonist (spironolactone or eplerenone). Cardiovascular morbidity caused by aldosterone excess can be decreased by either unilateral adrenalectomy or mineralocorticoid antagonist. In this review, we address the most relevant issues regarding PA screening, case confirmation, subtype classification, and treatment.

Figure 1. Algorithm for the detection and confirmation of primary aldosteronism.

A: aldosterone; DRC: direct renin concentration; PRA: plasma renin activity; CT: computed tomography.

Figure 2. A male patient, 69 years, with resistent hypertension for 30 years, diagnosed with PA. Hormonal data: aldosterone (A) = 24.4 ng/dL; DRC < 1.6 mU/mL (PRA 0.13); A/DRC ratio = 15.25; A/PRA ratio = 188. (A) Adrenal CT showing a 1.8 cm nodule at right adrenal gland and a 1.2 cm nodule at left adrenal gland. (B) Fluoroscopic imaging from AVS. (C) Analysis of AVS sampling showed lateralization of aldosterone production to the left side. Then, this patient had an adrenal incidentaloma on the right side and an aldosterone-producing adenoma on the left side. The patient underwent left adrenal adrenalectomy and had biochemical cure of PA.