Endocrine Abstracts

Adrenal venous sampling (AVS) is regarded as the gold-standard for the study of lateralisation of primary aldosteronism (PA) after its biochemical diagnosis. After catheterisation of both adrenal veins, confirmed by ratio of cortisol concentration in each adrenal vein and peripheral vein (selectivity index (SI)), lateralization is accepted if aldosterone/cortisol (A/C) ratio between both adrenal veins is over 3–4 (lateralization index (LI)), particularly if non-dominant vein has A/C level lower than peripheral vein. We present two cases of PA with selective AVS, but puzzling results about lateralisation: case 1 – woman (52 years), severe hypertension for the last 2 years, with elevated ratio aldosterone/plasmatic renin activity (RAR) and urinary aldosterone of 16.4 μg/24 h with hypernatriuria (340 mEq/24 h). First sample showed right SI of 44.3 and left SI of 12.2, and suggested bilateral production (LI: 1.12), with both adrenal A/C levels higher than peripheral vein. Second sample, 5 min later, showed right SI of 18.9 and left SI of 10.3, but indicated right lateralisation (LI: 3.2), coincident with adrenal tumour in CT, with A/C ratio in left vein lower than peripheral A/C ratio. Case 2 – woman (52 years), severe hypertension, only one selective sample in AVS (right SI: 10.83 and left SI: 15.32), A/C ratio in both veins lower than peripheral vein (18.2 and 8.5 vs 71.9). Normal CT scan. These two cases illustrate potential inaccuracies of AVS. These probably are due to superselective canalisation of adrenal veins, not draining venous effluent of the tumour producing aldosterone excess. In both cases, right SI were very high. These high ratios have been proposed as suggestive of very selective sampling, collecting blood of suppressed adrenal tissue, but not from the adenoma. Other possibility in the second case is anomalous drainage of pathologic tissue, by accessories veins not canulated in AVS, or an undetected extraadrenal source of aldosterone.