Adrenal venous sampling (AVS) is the gold standard test to differentiate the unilateral from the bilateral form in patients with primary
aldosteronism (PA) although it may be a difficult procedure, especially the successful cannulation of the right adrenal vein. In this report, we describe a 49-year-old female patient diagnosed with PA, after investigating resistant
hypertension and refractory
hypokalemia. Abdominal computed tomography scan revealed a 2.5 cm
adenoma on the right adrenal vein. AVS was performed under
cosyntropin infusion.
Aldosterone and
cortisol concentrations were obtained from the right and left adrenal veins and inferior vena cava (IVC).
Cortisol on each adrenal vein divided by
cortisol on IVC confirmed successful cannulation of the left side only, which makes it impossible to calculate the lateralization index (LI). From the data on the left adrenal vein and IVC, the
aldosterone-to-
cortisol ratio divided by the IVC
aldosterone-to-
cortisol ratio was less than 1.0, suggesting that the left adrenal vein was suppressed with the excess
aldosterone originating from the contralateral side (contralateral suppression index (CSI)). Right
adrenalectomy was performed; postoperative
hypoaldosteronism was confirmed. This report highlights the importance of CSI obtained in AVS when technical difficulties occur making it impossible to obtain LI, which is most commonly used to decide between surgical and clinical management of PA.