Based on adrenal vein sampling (AVS) results showing left adrenal vein cortisol ratio of 8.18, right adrenal vein cortisol ratio of 2.58, left aldosterone/cortisol ratio of 1.01, right aldosterone/cortisol ratio of 0.80, and a lateralization index of 1.26, what is the likely diagnosis and what medical management should be recommended?

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Last updated: October 5, 2026 • View editorial policy

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Bilateral Primary Aldosteronism - Proceed with Medical Management

Based on these AVS results showing inadequate lateralization (lateralization index 1.26, well below the required threshold of ≥4), this patient has bilateral primary aldosteronism and should be treated with mineralocorticoid receptor antagonist (MRA) therapy rather than surgery. 1

Interpretation of Your AVS Results

Successful Cannulation Confirmed

  • Left adrenal vein: Cortisol ratio 8.18 (adequate, >3-5 threshold)
  • Right adrenal vein: Cortisol ratio 2.58 (borderline/inadequate, ideally >3-5)

The right-sided cannulation is marginal, which introduces some uncertainty, but the lateralization calculation can still be interpreted.

Critical Finding: No Lateralization

Your lateralization index of 1.26 is far below the standard threshold of ≥4 required to diagnose unilateral disease. This indicates:

  • Both adrenal glands are producing excess aldosterone relatively equally
  • No dominant side exists that would benefit from surgical removal
  • This represents bilateral primary aldosteronism

Important Caveat About the Right-Sided Sampling

The right adrenal vein cortisol ratio of 2.58 is suboptimal. Recent evidence shows that partially successful AVS (when only one side is adequately cannulated) has limited utility and substantial overlap across PA subtypes, with previously proposed thresholds misclassifying up to 74% of cases 2. However, even accepting this borderline right-sided sample, your lateralization index remains non-diagnostic for unilateral disease.

Recommended Management Algorithm

1. Initiate MRA Therapy

Start with spironolactone 12.5-25 mg daily (or eplerenone 25-50 mg daily if side effects occur) 1:

  • Consider hypertension severity when dosing
  • May need to discontinue or reduce other antihypertensives initially
  • Titrate upward every 4-6 weeks based on response

2. Monitoring Parameters

Track the following to guide dose titration 1:

  • Blood pressure - target <130/80 mmHg
  • Serum potassium - monitor for hyperkalemia
  • Renal function - creatinine/eGFR
  • Renin levels - titrate MRA dose to raise renin from baseline if BP remains uncontrolled despite therapy

3. Dose Escalation Strategy

If hypertension persists and renin remains suppressed 1:

  • Increase MRA dose progressively (spironolactone up to 100-400 mg daily or eplerenone up to 100-300 mg daily)
  • Add additional antihypertensives as needed for BP control
  • The goal is to raise renin levels, indicating adequate MRA blockade

Why Surgery Is Not Recommended

The 2025 Endocrine Society guidelines are explicit: surgical therapy by unilateral adrenalectomy is offered to individuals with lateralizing PA 1. Your results do not demonstrate lateralization. Surgery in bilateral disease would:

  • Not cure the hypertension
  • Not normalize aldosterone excess from the remaining gland
  • Still require lifelong MRA therapy
  • Expose you to unnecessary surgical risk

Additional Considerations

Rule Out Concurrent Cortisol Excess

Given that you have an adrenal adenoma visible on imaging (implied by AVS being performed), perform a 1-mg dexamethasone suppression test to exclude mild autonomous cortisol secretion (MACS) 1. This is important because:

  • MACS can coexist with PA
  • Cortisol imbalance between adrenal veins can create false-positive lateralization on AVS 3
  • In your case, this would actually support the bilateral interpretation

Potential Pitfall: Assay Interference

Be aware that apparent bilateral aldosterone suppression (ABAS) can occur as an artifact of certain aldosterone immunoassays, particularly the Liaison assay 4. However, your results don't show ABAS - they show bilateral aldosterone production without lateralization, which is a different finding entirely.

If Repeat AVS Is Considered

Only pursue repeat sampling if 5:

  • Clinical suspicion for unilateral disease remains very high (age <35, marked hypokalemia, >1 cm unilateral adenoma)
  • Right-sided cannulation adequacy is questioned
  • Patient strongly desires surgical option

Otherwise, the current results are sufficient to guide medical management.

References

1
Guideline

primary aldosteronism: an endocrine society clinical practice guideline.

The Journal of clinical endocrinology and metabolism, 2025

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