Establishment of a rapid and simple liquid chromatography tandem mass spectrometry method for measuring aldosterone in urine.

Aldosterone (ALD) measurement plays a critical role in screening and diagnosis of primary aldosteronism. A variety of liquid chromatography tandem mass spectrometry (LC-MS/MS) methods for serum ALD have been developed. However, the few LC-MS/MS methods for 24 h urinary ALD that have been reported require tedious sample pretreatment procedure. This study aimed to establish a novel method for quantification of ALD in urine by LC-MS/MS. Urine samples from study participants were hydrolyzed and subjected to anion exchange solid phase extraction (SPE) followed by the detection of eluates by the negative electro-spray ionization and multiple reaction monitor modes. The established method was compared with two CLIA methods and 114 participants (M:39, F:75) were recruited to study the distribution of urinary ALD in an apparently healthy population. The pretreatment time was reduced to 4 h and the total run time for each sample was 4.5 min. The linearity of the method was in the range of 2-2000 pg/mL (r > 0.999); within laboratory coefficient variation (CV) and repeatability were both <5% and recovery was within 100% ± 10%. The established method showed good consistency with two CLIA methods with the correlation coefficients of 0.993(DiaSorin) and 0.980(Auto), respectively. In the 114 apparent healthy individuals, urinary ALD was 0.74-17.09 μg/24 h (P2.5-P97.5). The method showed an excellent performance of the method, prompting us to conclude that this method may be adopted in the clinic for routine testing and analysis of ALD in urine samples.