SAT-551 Sparing Confirmatory Tests in Primary Aldosteronism

Context: The current clinical guidelines suggest that confirmatory tests for primary aldosteronism (PA) may be excluded in some of patients who have elevated plasma aldosterone concentration (PAC) under plasma renin suppression. However, this has low priority evidence and is under debate in use of serum potassium. Objective: This study aimed to investigate an appropriate setting for sparing confirmatory tests in PA. Design and Setting: A retrospective cross-sectional study in a single referral center. Participants: This study included 327 patients who had hypertension under plasma renin suppression and underwent captopril challenge test (CCT) between January 2007 and April 2019. CCT results were used to diagnose PA. Main outcome measure: Diagnostic value of PAC and serum potassium in confirmation of PA. Results: Of the studied patients, 252 of 327 (77%) were diagnosed with PA. All 61 patients with PAC >30 ng/dl were diagnosed with PA. In patients with PAC between 20 and 30 ng/dl, 44 of 55 (80%) were diagnosed with PA, while all 26 with PAC between 20 to 30 ng/dl who had spontaneous hypokalemia were diagnosed with PA. Areceiver operator curve analysis showed that the sensitivity of diagnosis of PA is 100% in our patients, when PAC set at > 28.8 ng/dl and showed that the sensitivity of diagnosis of PA is 100% in our patients with spontaneous hypokalemia, who had PAC < 30 ng/dl, when PAC was set at > 19.2 ng/dl. While, the prevalence of PA was higher in patients with hypokalemia, who had PAC between 10 and 20 ng/dl than in those with PAC < 10 ng/dl. Collectively, 100 out of 102 (98%) with hypokalemia, who had PAC > 10 ng/dl were diagnosed as PA. The proportion of unilateral PA determined by adrenal vein sampling (AVS) was higher in patients who had PAC >30 ng/dl or those with spontaneous hypokalemia who had PAC between 20 and 30 ng/dl than those who did not meet the criteria (76% vs. 17%, P<0.001). Conclusion: Confirmatory tests in PA could be spared in patients who have typical features of PA and these patients had a high probability of unilateral PA on AVS.