Quantitation of Aldosterone in Serum or Plasma Using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).

Accurate determination of serum and plasma aldosterone is essential for screening, diagnosis, and subtype classification of primary aldosteronism (PA). Its measurement is also used in the investigation of adrenal incidentaloma, adrenal carcinoma, Addison's disease, congenital adrenal hyperplasia, renal artery stenosis, and renal tubular channelopathies. We describe a simple and robust method for the accurate and precise measurement of aldosterone in serum or plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS). After addition of internal standard, aldosterone is extracted from serum samples using supported liquid extraction (SLE) with methyl tert-butyl ether (MtBE). The MtBE is evaporated to dryness, and the sample is reconstituted with mobile phase before injection onto the LC-MS/MS and quantitation using an eight-point calibration curve. The assay calibration range is approximately 50-6500 pM (0.16-234 ng/dL) with total imprecision between 6.8% and 4.1% for concentrations between about 50 and 1000 pM, respectively.