Localization of aldosterone-producing adenoma: venous sampling in primary aldosteronism.

Adrenal venous sampling of blood was performed for nine patients with aldosterone-producing adenoma (APA). Measurement of adrenal venous aldosterone is useful for localization of APA but difficult, because catheterization of the right adrenal vein is not easy, and the blood is diluted by nonadrenal flow. To solve these problems, levels of aldosterone (A; ng/dl) and cortisol (C; micrograms/dl) were measured in samples from the left adrenal vein (LAV) and the inferior vena cava (IVC), and the LAV A/C and (LAV A/C)/(IVC A/C) ratios were calculated. These ratios were also obtained for 16 patients with essential hypertension. The adenoma could be localized in three of the nine cases by the measurement of aldosterone alone, but the use of a LAV A/C ratio greater than 5 x 10(-3) and a (LAV A/C)/(IVA A/C) ratio less than 1.0 as criteria separated the patients into those with a left APA, right APA, or essential hypertension. Consequently, adrenal venous sampling and the calculation of these ratios enables preoperative localization of APA with more accuracy, especially when the tumor is small or the result of CT and adrenal scintigraphy is not consistent.