Objective To explore the diagnostic value of captopril test (CCT) and saline infusion test (SIT) of liquid chromatography tandem mass spectrometry (LC-MS/MS) for patients with primary aldosteronism (PA).

Methods Clinical data of 127 hypertensive patients admitted to the Department of Endocrinology of Zhongshan Hospital from February 2018 to February 2019 were analyzed retrospectively. Serum aldosterone and renin levels were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Among the 127 patients, 111 patients underwent CCT test and 101 patients underwent SIT test. Surgery or spironolactone test was used as the gold standard for diagnosis. Totally, 57 patients were finally diagnosed with PA and 70 patients with essential hypertension. The changes in plasma aldosterone concentration (PAC), renin activity, and their ratios were analyzed before and after the experiment. The ROC curves were drawn up based on the aldosterone, aldosterone inhibition rate, and aldosterone/renin ratio (ARR). The AUC was compared and the best diagnostic cut-off point was analyzed.

Results PA patients had higher aldosterone and ARR levels, and a lower renin level. The AUC of aldosterone, ARR, and aldosterone inhibition rates were 0.876, 0.902, and 0.751 respectively after CCT; when the ARR was 6.5, the diagnostic sensitivity was 94.2% and the specificity was 78%. When the PAC was 34.8 pg/mL, the diagnostic sensitivity was 75.5%, and the specificity was 93.2%. The AUC of aldosterone, ARR, and aldosterone inhibition rates were 0.881, 0.823, and 0.652 after SIT. When the post-aldosterone cut-off point was 24 pg/mL, the diagnostic sensitivity was 87.2% and the specificity was 78.8%.

Conclusions Both post-ARR and PAC can be used as diagnostic indicators of PA after CCT, and the diagnostic cut-off points are 6.5 and 34.8 pg/mL, respectively. Post-PAC is the best diagnostic indicator of PA after SIT, and the diagnostic cut-off point is 24 pg/mL.