The value of midnight 1 mg dexamethasone suppression test combined with ACTH stimulation test in the diagnosis of primary aldosteronism subtypes

Abstract

Objective: To explore the value of the midnight 1 mg dexamethasone suppression test combined with adrenocorticotropic hormone (ACTH) stimulation test in the diagnosis of primary aldosteronism (PA) subtypes. Methods: A cross-sectional study. Clinical data of patients diagnosed with PA at the First Medical Center of Chinese PLA General Hospital from January 2020 to September 2022, who completed the midnight 1 mg dexamethasone suppression test combined with ACTH stimulation test, were analysed retrospectively. The clinical characteristics and trial results of patients with aldosterone-producing adenoma (APA) and idiopathic hyper aldosteronism (IHA)were compared. The efficacy of the midnight 1 mg dexamethasone suppression test combined with ACTH stimulation test in distinguishing APA and IHA was evaluated by drawing receiver operating characteristic (ROC) curves, and the cut-off value of the diagnostic indicator was determined with the maximum Youden index. Results: A total of 82 patients with PA were included, including 43 males and 39 females, aged (50.8±11.4) years old. They were divided into APA group (n=49) and IHA group (n=33) based on PA subtype. There was no statistically significant difference in body mass index, systolic and diastolic blood pressure between the two groups (all P>0.05). The blood potassium and orthostatic renin levels in the APA group were lower than those in the IHA group, and the differences were statistically significant (all P<0.001). The orthostatic plasma aldosterone concentration (PAC), orthostatic aldosterone to renin ratio (ARR), PAC before and after captopril challenge test(CCT), ARR after CCT, PAC before and after saline infusion test (SIT), and the proportion of unilateral lesions in the APA group were all higher than those in the IHA group, and the differences were statistically significant (all P<0.001). After the midnight 1 mg dexamethasone suppression test combined with ACTH stimulation test (30, 60, 90, 120 min), the PAC and PAC/cortisol levels in the APA group were significantly higher than those in the IHA group (all P<0.05). The PAC at 90 min showed the highest diagnostic capability according to the area under the ROC(AUC) (0.930,95%CI:0.874-0.986), and the Youden index was the highest at a PAC cut-off value of 39.05 ng/dl(0.766). The sensitivity and specificity for distinguishing APA from IHA were 91.8% and 84.8%, respectively. Conclusions: The midnight 1 mg dexamethasone suppression test with ACTH stimulation test could be useful for differentiating the subtypes of PA. Among them, the PAC and PAC/cortisol at 90 min showed best diagnostic efficacy.