[Comparison of predictive performance between midnight 1 mg dexamethasone suppression test combined with ACTH...

Objective: To compare the predictive efficacy of the midnight 1 mg dexamethasone suppression test combined with the adrenocorticotropic hormone(ACTH) stimulation test versus three prediction models for idiopathic hyperaldosteronism (IHA). Methods: Clinical data of patients diagnosed with aldosterone-producing adenoma (APA) and IHA at the First Medical Center of Chinese PLA General Hospital from January 2020 to August 2025 were retrospectively analyzed. Patients were definitively diagnosed by adrenal vein sampling (AVS), adrenal surgical pathology, and postoperative follow-up, and were divided into APA group and IHA group. The midnight 1 mg dexamethasone suppression test combined with the ACTH stimulation test, the Xiao model, the Kobayashi 2018 model, and the Umakoshi model were respectively used to predict IHA. The McNemar test was used to compare the sensitivity and specificity of the midnight 1 mg dexamethasone suppression test combined with the ACTH stimulation test with those of the three prediction models for IHA. Results: A total of 175 patients were enrolled, aged 54.0 (45.0, 59.5) years, including 85 males and 90 females. Among them, 82 were in the APA group and 93 in the IHA group. Using the criterion of 90 min plasma aldosterone concentration (PAC)<39.05 ng/dl after the midnight 1 mg dexamethasone suppression test combined with ACTH stimulation test to predict IHA, the sensitivity and specificity were 90.3% and 93.9%, respectively. Using the recommended predictive probability≥0.9 of the Xiao model as the criterion to predict IHA, the sensitivity and specificity for diagnosing IHA were 47.3% and 95.1%, respectively. Using the recommended score≥ 8 points of the Kobayashi 2018 model as the criterion to predict IHA, the sensitivity and specificity for diagnosing IHA were 16.1% and 98.8%, respectively. The Umakoshi model showed a sensitivity of 17.2% and a specificity of 97.6% for diagnosing IHA. The sensitivity of the midnight 1 mg dexamethasone suppression test combined with the ACTH stimulation test in diagnosing IHA was significantly higher than that of the Xiao model, the Kobayashi 2018 model, and the Umakoshi model (all P<0.001), while there were no statistically significant differences in specificity between the combined test and the three models (all P>0.05). Conclusions: The midnight 1 mg dexamethasone suppression test combined with the ACTH stimulation test shows higher sensitivity for predicting IHA than the Xiao model, Kobayashi 2018 model, and Umakoshi model, and its specificity is comparable to these three prediction models.