Cosyntropin stimulation in adrenal vein testing for Aldosteronoma

Once a diagnosis of primary aldosteronism is established, it is necessary to distinguish between adenoma and hyperplasia. Aldosteronomas, comprising one half to two thirds of cases, are almost always unilateral. Surgical excision generally cures or improves the hypertension while preserving adrenal function. Hyperplasia is almost always bilateral. Even bilateral adrenalectomy usually fails to cure the associated hypertension, so that additional treatment is needed. Methods for identifying and localizing aldosteronomas include adrenal venography, computed tomography, adrenal isotopic scanning and hormonal sampling via adrenal vein catheterization. Adrenal venograms involve a risk of serious complications, including adrenal infarction and retroperitoneal hemorrhage. Computed tomographic (CT) scans and radioisotopic adrenal scanning fail to detect small aldosteronomas and occasionally produce false-positive results. The exact role of these two noninvasive tests remains to be defined. Adrenal venous sampling, with over 90% sensitivity, sets the standard. Even this test, however, is subject to occasional error caused by episodic secretion of aldosterone. To overcome this shortcoming, multiple sampling and adrenocorticotropic hormone (ACTH)-stimulated sampling have recently been advocated. The latter technique, the simpler and cheaper of the two, has not been directly compared with the standard technique of unstimulated adrenal vein sampling. The following case of primary aldosteronism, in which results of both the computerized tomographic scan and unstimulated adrenal vein sampling were inconclusive, documents the increased sensitivity of cosyntropin-stimulated adrenal vein sampling.