MON-217 New Methods for Primary Aldosteronism Screening by Exploring the Values of Different Indicators and in Combination with Predictive Model

Background: Primary Aldosteronism (PA) is the most common cause of secondary hypertension. The endocrine society guidelines recommend case detection of PA by determining the aldosterone-renin ratio (ARR) under standard conditions, but the cut-off value of upright ARR varies greatly. In addition, as with all other biochemical tests, there are false positives and false negatives for upright ARR. In order to avoid false negative, some researchers have proposed plasma renin activity (PRA) < 1.0 ng/ml/h as a screening indicator. In order to avoid false positive caused by low PRA, Professor Young of the Mayo Clinic have proposed that the ARR combined with the plasma aldosterone concentration (PAC) > 15 ng / dL for PA screening. In 2019, Professor Young proposed PA screening positive when PAC≥10ng/dL and PRA<1.0 ng/ml/h. In addition, angiotensin II (AT-II) directly stimulates the synthesis of aldosterone. Compared with renin, the decrease of AT-II level and the increase of aldosterone to AT-II ratio (AA2R) may reflect the aldosterone autonomy secretion. However, whether these screening indicators are superior to upright ARR remains to be further verified. Therefore, either exploring the diagnostic efficacy of PAC, PRA, or AA2R as a screening indicator or even better developing a clinical prediction model combined with multiple indicators may provide a more accurate method for PA screening. Objective: To explore the value of different indicators and the logistic regression model (nomogram) for primary aldosteronism screening. Methods: The clinical data of 499 patients with PA and 479 patients with essential hypertension (EH) diagnosed by West China Hospital from 2009 to 2018 were retrospectively analyzed. The diagnostic performance of different screening methods was compared by plotting receiver operating characteristic curves (ROC). Results: The proportion of low potassium in PA group was higher than that in the EH group (86.20% vs. 36.50% P<0.001). The area under the ROC curve (AUC) of upright ARR was greater than that of upright AA2R, upright PRA, upright PAC, supine ARR, and lowest blood potassium (P<0.05); The AUC of logistic regression model (nomogram) [which consists of the upright PAC, the upright PRA, and the lowest blood potassium] was greater than that of upright ARR (96.3% vs. 94.6%, P<0.05). Conclusion: The upright ARR is the best single screening indicator; AA2R (radioimmunoassay) is not recommended for PA screening. Ultimately, the logistic regression model (nomogram) is superior to the upright ARR.