Clinical significance of LC-MS/MS aldosterone in screening for primary aldosteronism

Objective Retrospective analysis of clinical data of patients with primary aldosteronism in the past 2 years, to assess the value of liquid chromatography-mass spectrometric method (LC-MS/MS) aldosterone to renin ratio(ARR) and saline infusion test and its optimal cutoff in the diagnosis of primary aldosteronism(PA). Methods A total of 124 healthy volunteers were recruited to determine the normal reference range for LC-MS/MS aldosterone. 375 patients with high risk of primary aldosteronism were enrolled during March 2016 to November 2017. Among them, 241 patients underwent the saline infusion test. Receiver operating characteristic (ROC) analysis was performed to compare the diagnostic accuracie and the cutoff value of random ARR and post saline infusion test. Results The average level of LC-MS/MS aldosterone in healthy volunteers was(9.16±6.73)ng/dl (95% CI 2.34-22.18 ng/dl). Among 375 patients with high risk of PA, 143 patients with PA and 232 patients with essential hypertension (EH) were diagnosed. The area under the ROC curve(AUC ROC) of random ARR was 0.837(0.787-0.886), the cutoff point was 13.84 (ng/dl)/(ng/ml·h), with a sensitivity of 78.3% and a specificity of 79%. Using post-test plasma aldosterone concentration (PAC) for diagnosis, AUC ROC of the saline infusion test was 0.807(0.747-0.867), the cutoff point was 4.29 ng/dl, with a sensitivity of 90.6% and a specificity of 69.6%. Conclusion The normal range of LC-MS/MS aldosterone is 2.34-22.18 ng/dl. In our research, random ARR value above 13.84(ng/dl)/(ng/ml·h) can be the cutoff point in screening the suspected PA patients.PAC post- saline infusion test more than 4.29 ng/dl is recommended to confirm PA. Key words: Primary aldosteronism; Aldosterone; Liquid chromatography-mass spectrometric method; Aldosterone to renin ratio; Saline infusion test