From the Guidelines
Screening for primary aldosteronism should begin with measuring the aldosterone-to-renin ratio (ARR) in patients with hypertension, especially those with resistant hypertension, hypokalemia, adrenal incidentaloma, or family history of early-onset hypertension, as recommended by the most recent guidelines 1. The ARR test is currently the most accurate and reliable means of screening for primary aldosteronism, with a cutoff value of >30 ng/dL per ng/mL/hr when aldosterone is measured in ng/dL and renin activity in ng/mL/hr 1. Before testing, patients should discontinue medications that affect the renin-angiotensin-aldosterone system for at least 2 weeks, including spironolactone, eplerenone, amiloride, triamterene, ACE inhibitors, ARBs, diuretics, and beta-blockers, to ensure accurate results 1. However, the 2024 ESC guidelines suggest that ARR testing can be done in treated patients without changing or stopping their baseline BP-lowering medications, and the result should be interpreted in the context of the specific medication(s) the patient is taking 1. The test should be performed in the morning after the patient has been upright for at least 2 hours and seated for 5-15 minutes before blood sampling. An elevated ARR suggests primary aldosteronism, and positive screening results require confirmation with suppression testing, such as the oral sodium loading test, saline infusion test, fludrocortisone suppression test, or captopril challenge test 1. These tests evaluate whether aldosterone secretion can be suppressed, which doesn't occur in primary aldosteronism. Once confirmed, patients should undergo adrenal imaging (CT or MRI) and adrenal vein sampling to distinguish between unilateral (typically adenoma) and bilateral (typically hyperplasia) disease, which guides treatment decisions between surgical and medical management 1.
Some key points to consider when screening for primary aldosteronism include:
- The condition is often associated with resistant hypertension, hypokalemia, and adrenal incidentaloma 1
- The aldosterone-to-renin ratio is the most accurate and reliable means of screening for primary aldosteronism 1
- Medications that affect the renin-angiotensin-aldosterone system should be discontinued before testing, but the 2024 ESC guidelines suggest that ARR testing can be done in treated patients without changing or stopping their baseline BP-lowering medications 1
- Confirmation with suppression testing is necessary for positive screening results 1
- Adrenal imaging and adrenal vein sampling are necessary to distinguish between unilateral and bilateral disease 1
From the Research
Screening for Primary Aldosteronism
To screen for primary aldosteronism, the following steps can be taken:
- Measure plasma aldosterone concentration (PAC) and plasma renin activity (PRA) simultaneously, and calculate the aldosterone-to-renin ratio (ARR) 2, 3, 4, 5, 6
- Use a cutoff value for ARR, such as greater than 30, to indicate independent aldosterone secretion 3
- Use a cutoff value for basal PAC, such as 360 pmol/l, to differentiate lateralized primary aldosteronism from essential hypertensive patients 2
- Consider the patient's clinical presentation, such as resistant hypertension, hypokalemia, or an adrenal nodule, when interpreting the screening test results 3, 4, 5
Patient Selection for Screening
Screening for primary aldosteronism should be considered in the following patient groups:
- Patients with resistant hypertension 3, 5
- Patients with well-controlled hypertension and a first-degree relative with primary aldosteronism 3
- Patients with hypokalemia, an adrenal nodule, atrial fibrillation, obstructive sleep apnea, or a family history of an early stroke 3
- Patients with type 2 diabetes mellitus or obstructive sleep apnea, as they have an increased prevalence of primary aldosteronism 5
Confirmatory Testing
If the screening test is positive, confirmatory testing should be performed, such as: