Objective To evaluate the concordance rate between adrenal computed tomography (CT) and adrenal venous sampling (AVS) in the localization diagnosis of primary aldosteronism (PA), and to analyze the factors influencing this concordance.

Methods A total of 468 patients diagnosed with PA at the First Affiliated Hospital of Dalian Medical University from January 2020 to April 2025 who underwent both adrenal CT and successful AVS examination were included in this study. Using AVS as the gold standard, we evaluated the diagnostic performance of adrenal CT in the localization of PA by calculating sensitivity, specificity, positive predictive value, and negative predictive value. The Kappa statistic was employed to assess the agreement between adrenal CT and AVS in localization diagnosis. The clinical characteristics and biochemical indicators were compared between concordant and discordant groups. Subgroup analyses were further performed based on age and adrenal lesion type to explore factors affecting diagnostic concordance. Univariate and multivariate logistic regression analyses were used to identify independent predictors of concordance.

Results The Kappa coefficient between CT and AVS in the overall population was 0.207 (95%CI: 0.142 to 0.272), with sensitivity, specificity, positive predictive value, and negative predictive value of 50.2% (95%CI: 44.2% to 56.2%), 41.7% (95%CI: 34.6% to 49.1%), 56.4% (95%CI: 52.2% to 60.5%), and 35.8% (95%CI: 31.2% to 40.6%), respectively. Compared with the discordant group, the concordant group had younger age, lower serum potassium levels, and higher diastolic blood pressure, upright aldosterone/renin ratio (ARR), aldosterone concentration after saline infusion test, and 2 h aldosterone concentration after captopril challenge test. The concordance rate (69.4%,Kappa = 0.479, 95%CI: 0.248 to 0.710 vs. 44.9%, Kappa = 0.179, 95%CI: 0.112 to 0.246, Z = 2.440, P = 0.010), sensitivity (75.9% 95%CI: 56.5% to 89.7% vs. 47.2% 95%CI: 40.9% to 53.6%, χ² = 8.533, P = 0.003), and positive predictive value (84.6% 95%CI: 73.7% to 91.5% vs. 53.1% 95%CI: 48.6% to 57.6%, χ² = 9.349, P = 0.002) were significantly higher in the younger age group (＜35 years) compared to the middle-older age group ( ≥ 35 years). Further subgroup analysis in patients with unilateral lesions on CT showed a progressive decline in concordance with increasing age: 84.6% (＜35 years), 61.0% (35 to 50 years), 47.9% (50 to 65 years), and 40.0% (65 to 80 years) (χ² = 13.674, P＜0.001). The concordance rate was significantly higher in the unilateral adenoma group than in the non-adenoma group (60.8%, Kappa = 0.330, 95%CI: 0.232 to 0.428 vs. 43.8%, Kappa = 0.103, 95%CI: 0.019 to 0.225, Z = 2.850, P＜0.001). In patients with unilateral adenomatous lesions, the concordance rate was considerably higher in the younger group than that in the middle-aged and elderly group, with the difference approaching statistical significance (84.0%, Kappa = 0.623, 95%CI: 0.313 to 0.933 vs. 57.1%, Kappa = 0.292, 95%CI: 0.190 to 0.394, Z = 1.990, P = 0.050). Multivariate logistic regression analysis showed that age (OR = 0.977, 95%CI: 0.959 to 0.995, P = 0.014) and ARR (OR = 1.002, 95%CI: 1.000 to 1.003, P = 0.011) were independent predictors of concordance between CT and AVS localization diagnoses in the overall population. In patients undergoing saline infusion tests, age (OR = 0.972, 95%CI: 0.951 to 0.994, P = 0.013) and aldosterone concentration after saline infusion test (OR = 1.003, 95%CI: 1.000 to 1.007, P = 0.036) were independent predictors of concordance.

Conclusion Adrenal CT can be considered as an auxiliary examination for the localization diagnosis of PA in young (＜35 years) patients with unilateral adenoma on CT.