LAUSR

I n a recent issue of the Journal, Takeda et al. [1] reported the effect of adrenocorticotropic hormone (ACTH) stimulation during adrenal vein sampling (AVS) on primary aldosteronism treatment. In the report, they used a selectivity index, which was calculated as the adrenal vein to inferior vena cava ratio of cortisol, as an indicator for AVS success. They found that right adrenal vein and left central adrenal vein had selectivity index at least 5 in 89–93 and 86–93%, respectively, of the cases in post-ACTH-loading AVS (post-AVS) whereas they had selectivity index at least 2 in 73–78 and 67–84%, respectively, of the cases in basal AVS (basal-AVS). On the basis of the findings, the authors concluded that ACTH loading improved the success rate of AVS. However, the findings do not support the conclusion. In the methods, the authors described that they placed a catheter in each adrenal vein and performed AVS [1]. As post-AVS was performed from catheters placed in the same adrenal veins as those for basal-AVS, ACTH loading could not have affected the success rate of catheter insertion into adrenal veins. Thus, the difference in percentages of cases fulfilling cutoff values for selectivity index between basalAVS ( 2) and post-AVS ( 5) indicated that a cutoff value of selectivity index at least 2 in basal-AVS than that of selectivity index at least 5 in post-AVS had classified more cases as being unsuccessful. The difference just indicated that the cutoff value for selectivity index in basal-AVS was relatively higher than that in post-AVS. In addition, lower percentages of cases fulfilling cutoff values for selectivity index in left central adrenal vein than in left common trunk might indicate that a catheter in left AVS could have been inserted into inferior phrenic vein instead of central adrenal vein. Furthermore, the findings in outcomes of adrenalectomy indicate that cutoff values of a lateralizing index, which was calculated as the aldosterone to cortisol ratio (A/C) on the dominant side divided by that on the nondominant side, were inappropriate in both basal-AVS and post-AVS; adrenalectomy based on either lateralizing index greater than 2 for basal-AVS or lateralizing index greater than 4 for postAVS had about 70% clinical cure and 90% biochemical cure [1]. The findings indicate that several cases diagnosed as unilateral hypersecretion of aldosterone by either lateralizing index greater than 2 for basal-AVS or lateralizing index greater than 4 for post-AVS had bilateral hypersecretion. The cutoff values of lateralizing index for unilateral aldosterone hypersecretion need to be reconsidered; higher values for lateralizing index should be used to avoid unnecessary adrenalectomy. Suppression of aldosterone secretion from the contralateral side, which is indicated by the adrenal vein to inferior vena cava ratio of A/C less than 1, could be a better marker to indicate unilateral aldosterone hypersecretion [2–4].