Adrenal vein sampling ratios for localization
Both aldosterone and cortisol are measured in all AVS samples to determine the cortisol-corrected aldosterone values. The criteria used to determine lateralization of aldosterone hypersecretion depend on whether the AVS is done under cosyntropin administration. With cosyntropin administration, a cortisol-corrected aldosterone ratio from high-side to low-side of > 4:1 indicates the presence of a unilateral APA. In the absence of cosyntropin, some investigators consider a cortisol-corrected aldosterone lateralization ratio (high to low side) of > 2:1 as consistent with an APA. Suppression of aldosterone secretion in the contralateral adrenal is also suggestive of an APA.