Testing for Primary Aldosteronism in Patients With Hypertension

Lilian White, MD
October 27, 2025

Previously thought to be a rare disease, primary aldosteronism is estimated to affect 5% to 14% of patients with hypertension in the outpatient, primary care setting and 11% to 30% of patients with resistant hypertension. Resistant hypertension is defined as hypertension that persists despite the concurrent use of three different classes of antihypertensive medications or the use of four antihypertensive medications to achieve adequate blood pressure control. The prevalence of primary aldosteronism is notable in young adults with hypertension, patients with atrial fibrillation, and in those with hypertension and concomitant hypokalemia (16%, 43%, and 28%, respectively). However, only about 2% of patients undergo appropriate testing for primary aldosteronism.

Compared with patients with essential hypertension, those with primary aldosteronism vs essential hypertension are more likely to experience stroke, coronary artery disease, proteinuria, atrial fibrillation, left ventricular hypertrophy, and heart failure.

Testing for primary aldosteronism is recommended in patients with resistant hypertension, as well as patients with controlled hypertension and any of the following: atrial fibrillation, adrenal nodule, family history of stroke at younger than 40 years of age, hypokalemia, obstructive sleep apnea, and/or a first-degree relative with primary aldosteronism.

The 2025 AHA/ACC Guideline for the Prevention, Detection, Evaluation and Management of High Blood Pressure in Adults reaffirms tests in patients with resistant hypertension, regardless of the presence of hypokalemia. Some studies have demonstrated that less than 50% of patients with primary hypoaldosteronism had hypokalemia on laboratory testing, making it a less sensitive marker of the disease and supporting the new recommendations. A recent guideline on Primary Aldosteronism by the Endocrine Society takes it a step further, recommending that all patients with hypertension undergo testing for primary aldosteronism.

Testing for primary aldosteronism comprises measuring serum aldosterone and renin to calculate the ratio between the two. Screening is recommended in the morning, and the patient should not restrict sodium for a couple of days before testing. Assessing the level of potassium at the same time is helpful to interpret if the aldosterone level is appropriately compensating for the potassium level. Additionally, a positive response to treatment with spironolactone with improved blood pressure control can help support the diagnosis.

The sensitivity and specificity for aldosterone:renin concentration or activity vary by laboratory and testing method. A table in the Endocrine Society guideline offers generally recommended cutoffs but advises caution with interpretation of test results. Repeat testing may be needed in patients with a high pretest probability.

Importantly, testing for aldosterone and renin can be influenced by a variety of factors, making repeat testing sometimes necessary. Medications such as beta or alpha-2 blockers may falsely lower renin levels. Levels of aldosterone and renin may also be influenced by the presence of chronic renal disease, among other factors. Recommendations to minimize medication withholding and potential medication substitutes can be found in a table in the Endocrine Society guideline.

Testing all adults with hypertension for primary aldosteronism may improve diagnosis, but it may also lead to overdiagnosis, overtreatment, and increased costs. However, the risk of harm from treatment with spironolactone in a patient incorrectly diagnosed with primary aldosteronism is generally considered low. Some international modeling studies have demonstrated the cost-effectiveness of testing in patients with hypertension, arguing in favor of the reduced morbidity from timely treatment; however, the actual increased downstream costs of confirmatory testing and care have yet to be evaluated.

Additional information on the diagnosis and treatment of primary aldosteronism is available in a previously published AFP article.