What does an aldosterone level of 10 indicate?

What Does an Aldosterone Level of 10 ng/dL Mean?

An aldosterone level of 10 ng/dL is the critical threshold used to interpret screening tests for primary aldosteronism—when accompanied by an elevated aldosterone-to-renin ratio (ARR ≥30), this level indicates a positive screening test that requires confirmatory testing. 1

Context-Dependent Interpretation

The meaning of an aldosterone level of 10 ng/dL depends entirely on the clinical context and accompanying test results:

In Primary Aldosteronism Screening

• For a positive ARR screening test, plasma aldosterone concentration must be at least 10-15 ng/dL in addition to the elevated ratio (ARR ≥30 when aldosterone is measured in ng/dL and renin activity in ng/mL/h). 1
• This 10 ng/dL threshold ensures adequate specificity—without this minimum aldosterone level, the ARR alone has insufficient diagnostic accuracy. 1
• An aldosterone of exactly 10 ng/dL with ARR ≥30 represents the borderline for a positive screen and mandates confirmatory testing (saline suppression test or oral sodium loading). 1

In Confirmatory Testing (Post-Saline Suppression)

• After saline suppression testing, aldosterone ≥10 ng/dL (≥277 pmol/L) confirms autonomous aldosterone production and establishes the diagnosis of primary aldosteronism. 2
• Failure to suppress aldosterone below 5 ng/dL after 2L normal saline infusion over 4 hours is the traditional diagnostic cutoff, but levels ≥10 ng/dL post-suppression are definitively abnormal. 1

In the Continuum of Dysregulated Aldosterone

• Recent evidence demonstrates that dysregulated aldosterone production exists on a continuum—even individuals with post-saline aldosterone levels below the traditional 10 ng/dL threshold may have lateralizing disease amenable to surgical treatment (15% in one study). 2
• The 10 ng/dL cutoff represents a practical diagnostic threshold, but clinically significant aldosterone excess can occur at lower levels in the context of low renin. 2

Critical Clinical Pitfalls

Do not rely on hypokalemia to screen for primary aldosteronism—it is absent in 50% of cases, and an aldosterone of 10 ng/dL with suppressed renin warrants full evaluation regardless of potassium levels. 1

Patient preparation is essential for accurate interpretation: patients must be potassium-replete before testing (hypokalemia suppresses aldosterone production), and interfering medications (beta-blockers, diuretics, ACE inhibitors/ARBs) should be discontinued when clinically feasible. 1

Blood collection timing matters: draw blood in the morning with the patient seated for 5-15 minutes after being out of bed for 2 hours to ensure standardized conditions. 1

Next Steps When Aldosterone is 10 ng/dL

If the aldosterone level is 10 ng/dL:

• Calculate the ARR: If ARR ≥30, proceed to confirmatory testing (saline suppression test or oral sodium loading with 24-hour urine aldosterone measurement). 1
• If confirmatory testing is positive: Obtain non-contrast CT of the adrenals, followed by adrenal venous sampling in surgical candidates to determine lateralization (CT alone is insufficient—up to 25% would undergo unnecessary adrenalectomy based on imaging alone). 1
• Treatment depends on lateralization: Laparoscopic unilateral adrenalectomy for unilateral disease (cures hypertension in ~50%, improves it in virtually 100%); mineralocorticoid receptor antagonists (spironolactone or eplerenone) for bilateral disease. 1