On the consistency of different methods for detecting aldosterone concentration in blood

Objective To evaluate the consistency of different methods for detecting aldosterone concentration in blood and to establish a reference interval of serum aldosterone concentration by liquid chromatography-tandem mass spectrometry(LC-MS/MS). Methods Concentrations of blood aldosterone were measured by LC-MS/MS, chemiluminescent assays (Diasorin, Domestic A and B systems) and radioimmunoassay (RIA) in 138 healthy adults, 67 patients with essential hypertension and 23 patients with primary aldosteronism. Results Aldosterone concentrations measured by various methods were quiet different(P 0.05) between CLIA(Domestic B) and LC-MS/MS, 0.338(P<0.01) as well as between RIA and LC-MS/MS. Bland-Altman analysis for the measurements showed poor consistency among methods for aldosterone concentrations. The reference interval was 15.2-222.2 pg/ml for serum aldosterone concentrations by LC-MS/MS. Conclusions There are significant differences of blood aldosterone concentrations determined by different methods. Clinically, a specified reference interval might be needed while using different methods. Key words: Aldosterone; Liquid chromatography-tandem mass spectrometry; Chemiluminescent assays; Radioimmunoassay