Efficacy of Screening and Confirmatory Tests of Primary Aldosteronism in Diagnosing AldosteroneProducing Adenoma

Objective To assess the efficacy of screening and confirmatory tests of primary aldosteronism (PA) in diagnosing aldosterone producing adenoma (APA). Methods Clinical data of 167 hypertensive patients were retrospectively reviewed, including 93 patients with APA and 74 patients with essential hypertension (EH). The area under curves (AUC) of receiver operating characteristic (ROC) curves were compared among the five indicators: supine plasma aldosterone concentration (PAC), absolute PAC values and PAC drop rates post saline infusion test (SIT) and captopril challenge test (CCT). Results APA patients had higher supine PAC, higher percentage of third degree hypertension, and lower serum potassium level than EH patients (P<0.05). Compared with EH patients, APA patients had lower PAC change rates, post posture change and SIT (P<0.05), but similar post CCT (P>0.05). The AUC of supine PAC reached 0.975. Higher AUC was found in absolute PAC values post SIT compared with PAC droop rates (0.984 vs. 0.680, P<0.001). Similar results were also found with CCT (0.949 vs. 0.538, P<0.001). A cut-off of supine aldosterone renin ratio (ARR) >30 and supine PAC>17.8 ng/dL had 96.8% sensitivity and 90.5% specificity. A cut-off of 14.59 ng/dL PAC post SIT had 90.2% sensitivity and 97.3% specificity. A cut-off of 19.11 ng/dL PAC post CCT had 88.8% sensitivity and 95.9% specificity. Conclusion Screening tests using supine ARR>30 plus supine PAC>17.83 ng/dL are preferred with high sensitivity and specificity. The absolute values of PAC post SIT and CCT are recommended for confirming APA.