A LC-MS/MS method for the simultaneous quantitative determination of aldosterone, its precursor 18-hydroxycorticosterone and its metabolite tetrahydroaldosterone in human urine

Aldosterone (ALD), its precursor 18-hydroxycorticosterone (18-OHB) and its metabolite tetrahydroaldosterone (TH-ALD) are important biomarkers for the diagnosis of primary aldosteronism (PA). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is increasingly utilized in the detection of small molecules of hormones because it has advantages in terms of specificity and sensitivity. The objective of this study is to develop a new LC-MS/MS method for the simultaneous quantification of ALD (free), 18-OHB, and TH-ALD in human urine and attempt to diagnose primary aldosteronism using different indicators. The urine samples were treated with a solid-phase extraction pretreatment technique and the three analytes were separated on a reversed-phase column and detected on a triple quadrupole mass spectrometer. The established method was validated according to CLSI C62-A standard guidelines. The calibration ranges from 25 pg/mL to 5000 pg/mL for aldosterone (free), 18-hydroxycorticosterone and tetrahydroaldosterone, and the lower limit of quantification for these three analytes was 25 pg/mL. The matrix effects and recoveries of these three analytes ranged from 85.1 % to 115 % and from 86.3 % to 114 %, respectively. The intra-day and inter-day precision ranged from 1.29 % to 6.78 % and from 1.77 % to 8.64 %, respectively. The performance of the method met the requirements of the guidelines. 40 clinical urine samples including 22 PA patients and 18 non-PA patients were detected, and the ROC curves of three diagnostic indicators were established. The area under the curve (AUC) of ALD (free) is the biggest, so ALD (free) was the best compound to be used as a diagnostic indicator in this study. When the cut-off point was taken as 141 ng/24-h, the sensitivity was 72.7 % and the specificity was 88.9 %. We developed and validated an LC-MS/MS method for the simultaneous quantification of ALD (free), 18-OHB and TH-ALD in human urine. Our study provides a reference for the use of new biomarkers for the diagnosis of primary aldosteronism.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) based assay for the simultaneous quantification of 18-hydroxycorticosterone, 18-hydroxycortisol and 18-oxocortisol in human plasma

18-hydroxycorticosterone (18-OHB), 18-hydroxycortisol (18-OHF) and 18-oxocortisol (18-OXOF) are important biomarkers for the diagnosis of subtypes of primary aldosteronism. The detection of these three analytes by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is free from structurally similar compounds. The aim of this study was to develop and validate a new LC-MS/MS assay for the simultaneous quantification of 18-OHB, 18-OHF and 18-OXOF in plasma and to establish a reference intervals for apparently healthy population. Plasma samples were prepared by solid phase extraction and separated in an ultra-high performance reversed phase column. MS detection was achieved using a triple quadrupole mass spectrometer in both positive and negative ionization modes. The developed assay was then validated against standard guidelines. We collected 691 plasma samples from apparently healthy individuals (M:398, F:293) to establish the reference intervals. The analytes were separated and quantified within 5 min. The newly developed method demonstrated linearity for the detected steroid concentration in range of 5 to 3000 pg/ml for 18-OXOF (r² = 0.999) and 20 to 3000 pg/ml for 18-OHB (r² = 0.997) and 18-OHF (r² = 0.997). The lower limit of quantification (LLOQ) was 2.5 pg/ml, 20 pg/ml and 20 pg/m for 18-OXOF, 18-OHB and 18-OHF respectively. Specificity, precision, accuracy and stability were tested, and met the requirements of the guidelines. 18-OHB was higher in females than in males, but 18-OHF were higher in males than females. The reference intervals of 18-OHB, 18-OHF and 18-OXOF for both genders together were 90.5-1040.6 pg/ml, 224.4-1685.2 pg/ml, 4.0-70.5 pg/ml, respectively. Age was also an important factor influencing the levels of these three hormones. We have developed a sensitive and reliable method for the simultaneous quantification of 18-OHB, 18-OHF, and 18-OXOF. Our work provides a reference interval for the clinical application of these three steroid hormones.