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A 68-year-old woman with a longstanding history of poorly controlled hypertension is evaluated for primary aldosteronism. On physical examination, blood pressure is 176/105 mm Hg. Cardiac examination reveals an S3 gallop. The lungs are clear to auscultation. Plasma renin activity is 0.06 ng/mL (0.06 μg/L) per hour and 24-hour urine aldosterone excretion is 18 µg (49.93 nmol/d).
An adrenal CT scan reveals a 1.5-cm solitary nodule in the left adrenal gland. The right adrenal gland appears normal but may be slightly enlarged.
Which of the following is the most appropriate next step in this patient's management?
A Laparoscopic left adrenalectomy
B Adrenal vein sampling for aldosterone and cortisol
C Renal arteriography
D Dexamethasone suppression test
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A Laparoscopic left adrenalectomy
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Answer and Critique (Correct Answer = B)
Key Point
The most common causes of primary hyperaldosteronism are aldosterone-producing adenoma (Conn's syndrome) and bilateral adrenal hyperplasia.
The most appropriate next step in this patient's management is adrenal vein sampling for aldosterone and cortisol. This patient's suppressed plasma renin activity and high urinary aldosterone excretion are consistent with primary hyperaldosteronism. The most common causes of this condition are aldosterone-producing adenoma (Conn's syndrome) and bilateral adrenal hyperplasia.
Aldosterone-producing adenoma can be resolved surgically by removal of the involved adrenal gland, but adrenalectomy usually is associated with a cure rate of only 50% to 60%. Adrenalectomy is not curative in this setting because smaller, functioning nodules may be present in the contralateral adrenal gland that are too small to visualize on CT scanning; the nodule observed on a CT scan may not be a functional adenoma; primarily essential hypertension may be present. In older patients, coexistent essential hypertension is more likely to be present and adrenalectomy is less likely to be curative. Therefore, adrenal vein sampling to document unilateral secretion of aldosterone from the adrenal gland with the nodule and suppression of aldosterone secretion from the contralateral gland is recommended before surgery, particularly in patients >40 years of age. Simultaneous cortisol measurements document that the sample was obtained from the adrenal vein, where cortisol levels should be higher, rather than the inferior vena cava.
Laparoscopic adrenalectomy is not recommended without adrenal vein sampling in older patients with suspicion for primary aldosteronism. Iodocholesterol scanning, which distinguishes functional adrenal nodules from nonfunctional incidental masses or carcinomas, would be an appropriate alternative to this study. Even if this patient declines further testing and surgery, the appropriate medical treatment would be aldosterone blockade. Therefore, renal arteriography is not warranted. A thiazide diuretic would exacerbate her hypokalemia. An inherited chimeric gene resulting in increased aldosterone production, which is abnormally regulated by adrenocorticotropic hormone, causes glucocorticoid-remediable hyperaldosteronism. The biochemical (such as low potassium levels, high sodium levels, metabolic alkalosis) and hormonal (such as low renin activity levels, high aldosterone levels) changes associated with this condition and aldosterone-producing adenomas are similar. However, a dexamethasone suppression test is not indicated because glucocorticoid-remediable hyperaldosteronism is not associated with an adrenal adenoma
