Adrenal vein sampling for primary aldosteronism: the assessment of selectivity and lateralization of aldosterone excess baseline and after adrenocorticotropic hormone (ACTH) stimulation

Background Adrenal vein sampling is crucial for identifying the primary aldosteronism subtypes, but the cutoff values for ascertaining selectivity of catheterization and lateralization of aldosterone secretion remain controversial. Objectives To investigate the safety of adrenal vein sampling, the cutoff values for the selectivity and lateralization indexes, and the effect of adrenocorticotropic hormone stimulation on selectivity index and lateralization index performance. Design We assessed the proportion of selective adrenal vein sampling at different selectivity index cutoff values in 151 consecutive patients with primary aldosteronism undergoing bilaterally simultaneous adrenal vein sampling. Aldosterone-producing adenoma was diagnosed on the basis of the evidence of primary aldosteronism and lateralized aldosterone secretion, adenoma at pathological examination, and normokalemia, and correction of primary aldosteronism and cure or improvement of hypertension at follow-up. In 44 patients with bilaterally selective adrenal vein sampling and unequivocal diagnosis of aldosterone-producing adenoma on the basis of all these criteria, we examined the cutoff values of the lateralization index for assessing the lateralization of aldosterone excess and the effect of adrenocorticotropic hormone stimulation on selectivity index and lateralization index. Results Adrenal vein rupture occurred in one case (0.7%). Bilaterally selective adrenal vein sampling decreased steadily (from 79.9 to 40.2%) with increase in the selectivity index cutoffs from 1.1 to 5.0. Likewise, the proportion of correctly identified aldosterone-producing adenomas decreased (from 95.5 to 43.2%) with increase in lateralization index cutoffs from 1.125 to 5.0. Adrenocorticotropic hormone improved the assessment of selectivity but exerted a confounding effect on lateralization index. Conclusion Adrenal vein sampling is safe; increasing the selectivity index cutoffs lowers the number of usable adrenal vein samplings; higher lateralization index cutoff values lead to missing a proportion of aldosterone-producing adenomas. The improved selectivity rate provided by adrenocorticotropic hormone stimulation should be weighed against the loss of correct lateralization.