CT Scans Miss Half of Aldosterone Sources in Primary Aldosteronism
New research shows cross-sectional imaging disagrees with tissue-level aldosterone mapping in nearly half of surgical PA patients.
Summary
Primary aldosteronism is a common, treatable cause of high blood pressure, but choosing which adrenal gland to remove requires accurate localization. This study compared CT/MRI imaging findings against direct tissue staining for the aldosterone-producing enzyme CYP11B2 in 173 surgical patients. Imaging and tissue results matched in only about half of cases. Nearly half showed discrepancies — extra nodules that weren't producing aldosterone, missed active tissue, or additional hormone-producing areas invisible on scans. Patients whose imaging and tissue results agreed were more likely to have specific genetic mutations (KCNJ5), while mismatches were linked to CACNA1D mutations. The findings suggest relying on imaging alone to guide adrenal surgery could lead to incomplete or incorrect treatment, reinforcing the importance of adrenal vein sampling before surgery.
Detailed Summary
Primary aldosteronism (PA) is the most common cause of secondary hypertension, affecting up to 10% of hypertensive patients. When one adrenal gland is the culprit, surgical removal can be curative — but only if the correct gland is targeted. Adrenal vein sampling (AVS) is the gold standard for lateralization, yet many centers skip it and rely on CT or MRI imaging instead, partly due to AVS's technical difficulty and limited availability.
This retrospective cohort study from the University of Michigan examined 173 patients who underwent unilateral adrenalectomy for PA between 2012 and 2024. Researchers compared blinded cross-sectional imaging interpretations against CYP11B2 immunohistochemistry (IHC) — a tissue stain that directly identifies aldosterone-producing cells — performed on the removed adrenal glands.
The results were striking. Imaging and IHC findings corresponded in only about half of patients. In 47% of cases, there were meaningful discrepancies: imaging showed extra nodules that turned out to be non-functional, bilateral nodules were present when only one side was truly active, or imaging appeared normal while IHC revealed discrete aldosterone-producing foci. In 20 additional patients, imaging correctly identified a lesion but missed additional CYP11B2-positive areas in the same gland.
Genetic analysis added nuance: concordant cases were enriched for KCNJ5 mutations — typically associated with classic, discrete adenomas — while discordant cases more often carried CACNA1D mutations, which tend to produce more diffuse or atypical aldosterone production patterns.
The clinical implication is clear: cross-sectional imaging alone is an unreliable guide for surgical decision-making in PA. Even when a nodule is visible, it may not be the aldosterone source, and active tissue may be invisible on scans. These findings strengthen the case for AVS as a prerequisite for adrenalectomy and highlight the need for broader AVS access.
Key Findings
- Imaging and CYP11B2 tissue staining agreed in only 53% of lateralized PA patients undergoing adrenalectomy.
- 47% of patients showed discrepant findings, including non-functional nodules on imaging and missed active tissue.
- KCNJ5 mutations correlated with imaging-IHC concordance; CACNA1D mutations were more common in discordant cases.
- 20 patients had imaging-confirmed lesions but additional undetected aldosterone-producing foci in the same gland.
- Results caution strongly against using CT/MRI alone to guide surgical targeting in primary aldosteronism.
Methodology
Single-center retrospective cohort study of 173 PA patients who underwent unilateral adrenalectomy at the University of Michigan between 2012 and 2024. Cross-sectional imaging was interpreted in blinded fashion and compared against CYP11B2 immunohistochemistry on formalin-fixed paraffin-embedded adrenal tissue. Genetic mutation data (KCNJ5, CACNA1D) were incorporated for subgroup analysis.
Study Limitations
This summary is based on the abstract only, as the full text is not open access. The study is a single-center retrospective cohort, which may limit generalizability. All patients had already undergone surgery, so the analysis cannot directly assess how imaging-guided decisions would have affected outcomes in a prospective setting.
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