SAT-074 Using Ipsilateral and Contralateral Ratios from Adrenal Vein Samples to Identify Functioning Adrenal Adenoma in Patients with Primary Aldosteronism

Primary aldosteronism (PA), a common cause of secondary hypertension, has a higher risk of cardiovascular complications than essential hypertension. To determine specific treatment for PA, subtype classification by adrenal venous sampling (AVS) is used. Sometimes, bilateral adrenal vein cannulation cannot be successfully performed. Previous studies have tried to use the data from unilateral adrenal vein cannulation, namely ipsilateral ratio (IR) and contralateral ratio (CR) in terms of aldosterone level, to interpret lateralization of aldosterone secretion. However, the cut-off values are still inconclusive. The objective of our study was to determine diagnostic performance using IR and CR in terms of adenoma location to identify functioning adrenal adenoma in patients with PA. Methods: The PA patients with unilateral adrenal adenoma who underwent AVS were included. The exclusion criteria were unsuccessful bilateral AVS or equivocal lateralization index (LI), i.e., values between 3 and 4. Successful AVS was assessed by sensitivity index, defined by adrenal vein/inferior vena cava (IVC) cortisol ratio of more than 5. The LI was calculated by dividing the higher aldosterone/cortisol ratio (dominant side) by the lower aldosterone/cortisol ratio (non-dominant side) obtained from adrenal vein samples. The LI of more than 4 indicated unilateral PA and those of less than 3 indicated bilateral PA. The IR was aldosterone/cortisol ratio at the side of adenoma divided by aldosterone/cortisol ratio at IVC. The CR was aldosterone/cortisol ratio at the side contralateral to the adenoma divided by aldosterone/cortisol ratio at IVC. Area under the receiver operating characteristic (ROC) curve was used to determine the diagnostic performance. The cut-off values giving the best sensitivity and specificity were determined. Results: Forty-three patients were included for analysis. Most patients (69.8%) were female with mean onset of hypertension at the age of 40.8±8.8years (SD). Median plasma aldosterone concentration and plasma aldosterone/renin activity ratio were 59.0 (IQR 44.2, 97.4) ng/dL and 1,020 (IQR 235, 4257), respectively. Thirty-five patients had unilateral PA, 7 patients had bilateral adrenal hyperplasia and 1 patient had unilateral adrenal hyperplasia. The area under ROC curve for identifying patients with functioning adrenal adenoma was 0.92 (95% CI; 0.81-1.00) when using IR and 0.78 (95% CI; 0.56-0.98) when using CR. The IR with the cut-off value of 1.2 had 89% sensitivity and 88% specificity. The CR with the cut-off value of 0.3 had 80% sensitivity and 75% specificity. Conclusion: The IR could be used to identify the functioning adrenal adenoma in PA patients with high accuracy.