A 42-year-old woman presents with hypertension, hypokalemia, and an aldosterone-to-renin ratio (ARR) of 42 ng/dL per ng/mL/hr. Confirmatory testing with saline infusion shows plasma aldosterone > 10 ng/dL post-infusion. CT adrenals show a 1.6 cm right adrenal adenoma. What is the recommended next step before surgical planning?
- A Proceed directly to right adrenalectomy
- B Adrenal venous sampling (AVS) ✓
- C Repeat CT adrenals with contrast
- D 131I-NP-59 scintigraphy
Explanation
Current Endocrine Society guidelines recommend adrenal venous sampling (AVS) in all patients with primary aldosteronism who wish to pursue surgical cure, as CT imaging has a 20–40% rate of misidentifying the source of autonomous aldosterone secretion (bilateral disease can appear as unilateral on CT, and small contralateral adenomas may be missed). AVS lateralises the hypersecretion with a lateralisation ratio ≥ 4:1 confirming unilateral disease. Proceeding directly to surgery based on CT alone risks operating on the wrong side. NP-59 scintigraphy has lower sensitivity and is rarely used when AVS is available.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.