[Study of appropriate cut-off for diagnosis of primary aldosteronism by seated saline suppression test based on liquid chromatography with tandem mass spectrometry]

Objective: To investigate the appropriate cut-off for diagnosis of primary aldosteronism (PA) by seated saline suppression test (SSST) based on liquid chromatography with tandem mass spectrometry (LC-MS/MS). Methods: In this cross-sectional study, patients who underwent SSST for suspected PA in the First Affiliated Hospital of Chongqing Medical University from January 2018 to March 2022 were evaluated. Briefly, 300 patients with PA and 119 with essential hypertension (EH) were included. Plasma aldosterone concentration (PAC) after SSST was determined by LC-MS/MS. Primary aldosteronism confirmatory testing (PACT) score was used as the reference standard for diagnosis of PA, and receiver operating characteristic (ROC) curve was used to explore the cut-off value. Results: The average age of the PA group was (50.8±10.5) years, and males accounted for 53.00% (n=159); the average age of the EH group was (49.4±11.2) years, and males accounted for 26.89% (n=32). The area under the ROC curve of PAC post-SSST was 0.819 (95%CI 0.775-0.862). When 40 pg/ml (110.8 pmol/L) was selected as the appropriate cut-off for diagnosis of PA, the sensitivity was 83.67% (95%CI 78.88%-87.56%) and specificity was 60.50% (95%CI 51.10%-69.21%). Thus, 95.09% (155/163) of patients with unilateral PA could be identified. Conclusion: PAC after SSST determined by LC-MS/MS has high efficacy for diagnosis of PA, and 40 pg/ml is recommended as the appropriate cut-off value.