Preoperative lateralisation of aldosteronomas by aldosterone/cortisol ratios in adrenal venous plasma

Data from adrenal scintigraphy with 6 beta-[131I]-iodomethyl-19-norcholesterol (AS), computed tomography (CT), adrenal venography and adrenal venous sampling were compared for their accuracy in locating small aldosteronomas in 17 patients. Final confirmation of location was by surgery. Seventeen out of 18 adrenals whose aldosterone/cortisol (A/C) ratio was 5.0 x 10(-3) or higher were found to have aldosteronomas (94.4%). All 14 adrenals whose A/C ratios were less than 5.0 x 10(-3) contained no aldosteronomas (100%). AS successfully lateralised nine out of 17 aldosteronomas (52.9%), CT 3 out of 5 (60.0%), adrenal venography 12 out of 17 (70.6%), adrenal venous aldosterone concentration 12 out of 15 (80.0%). The most frequent problem with adrenal venous sampling was the varying degrees of mixture with non-adrenal venous blood, mainly from renal vein and inferior vena cava blood. The A/C ratio of adrenal venous plasma proved to be the most useful diagnostic tool, using cortisol concentration as an indicator of any non-adrenal venous mixture.