There is an urgent need to develop a highly reliable method of measuring aldosterone to aid detection of endocrine forms of hypertension such as primary aldosteronism. This study sought to clinically validate an LC/MS/MS approach to aldosterone measurement in human plasma.

Methods

Samples (EDTA and Li+ heparin plasma, and serum from separator and plain clot tubes) were prepared and aldosterone measured using a Symbiosis Pharma on-line sample preparation/LC system coupled to a Quattro Premier tandem-mass spectrometer using d7-aldosterone internal standard [1]. EDTA samples were also analysed by radioimmunoassay (RIA; DPC Coat-a-count). To establish a normal range for LC/MS/MS aldosterone, blood was collected midmorning from 97 normotensive seated subjects.

Results

The method was linear over the analytical range of 2.5 to 200ng/dL (r2>0.994, n=14). Inter- and intra-day accuracy and imprecision for quality control samples (6.0, 40, 150ng/dL) were 92.2% to 102% and <6.3% respectively (n=5). Lower limit of quantification was 2.5ng/dL (inter- and intra-day accuracy and imprecision 91.4-94.5% and <9.5%; n=5). No interferences were seen in plasma from Addison