title: Combination of LC-MS/MS aldosterone and automated direct renin in screening for primary aldosteronism.
abstract: BACKGROUND
  Aldosterone to renin ratio (ARR) is used in screening for primary aldosteronism (PA). However, there are only few studies on the influence of assay methods on ARR and its cut-off limits.
  
  
  METHODS
  Plasma direct renin immunoreactivity by chemiluminescence immunoassay (DR) was compared to renin activity assay (PRA), and a specific liquid chromatography-mass spectrometric method (LC-MS/MS) to radioimmunoassay (RIA) for plasma aldosterone. There were 75 samples for renin assays, and 42 samples of 39 patients for both renin and aldosterone assays. PA screening was considered positive if ARR by the aldosterone RIA:PRA was ≥800pmol/L:μg/L/h or by LC-MS/MS:DR≥44pmol/L:ng/L.
  
  
  RESULTS
  The correlation between the DR and PRA methods (n=75, r(2)=0.845) and between LC-MS/MS and RIA (n=42, r(2)=0.973) was high in general, but low between the renin methods (n=49, r(2)=0.435) at low PRA values. When ARR was used in screening for PA, there were three divergent cases (positive only by alternative methods), but when applied in combination with criteria for elevated aldosterone, the methods showed good agreement, resulting in eight positive and 31 negative screening results.
  
  
  CONCLUSIONS
  The automated DR assay combined with LC-MS/MS method for aldosterone provides a rapid, reliable, and specific method for screening of PA.
authors.affiliation: Institute of Clinical Medicine/Internal Medicine, University of Eastern Finland, Yliopistonranta 1, P.O.B. 1627, 70211 Kuopio, Finland; Department of Medicine, Kuopio University Hospital, Puijonlaaksontie 2, P.O.B. 100, 70029 Kuopio, Finland. Electronic address: auni.juutilainen@kuh.fi.
authors.forename: Auni
authors.initials: A
authors.lastname: Juutilainen
authors.affiliation: Department of Clinical Chemistry, Eastern Finland Laboratory Centre, P.O.B. 1700, Puijonlaaksontie 2, 70211 Kuopio, Finland.
authors.forename: Kari
authors.initials: K
authors.lastname: Savolainen
authors.affiliation: Department of Clinical Chemistry, Eastern Finland Laboratory Centre, P.O.B. 1700, Puijonlaaksontie 2, 70211 Kuopio, Finland.
authors.forename: Jarkko
authors.initials: J
authors.lastname: Romppanen
authors.affiliation: HUSLAB Helsinki University Central Hospital, PL 720, 00029 HUS Helsinki, Finland.
authors.forename: Ursula
authors.initials: U
authors.lastname: Turpeinen
authors.affiliation: HUSLAB Helsinki University Central Hospital, PL 720, 00029 HUS Helsinki, Finland.
authors.forename: Esa
authors.initials: E
authors.lastname: Hämäläinen
authors.affiliation: Department of Medicine, Kuopio University Hospital, Puijonlaaksontie 2, P.O.B. 100, 70029 Kuopio, Finland.
authors.forename: Janne
authors.initials: J
authors.lastname: Kemppainen
authors.affiliation: Department of Medicine, Kuopio University Hospital, Puijonlaaksontie 2, P.O.B. 100, 70029 Kuopio, Finland.
authors.forename: Leena
authors.initials: L
authors.lastname: Moilanen
authors.affiliation: Department of Clinical Chemistry, University of Eastern Finland and Eastern Finland Laboratory Centre, P.O.B. 1700, Puijonlaaksontie 2, 70211 Kuopio, Finland.
authors.forename: Kari
authors.initials: K
authors.lastname: Pulkki
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000450:Aldosterone / Q000097:blood*; D001331:Automation; D001774:Blood Chemical Analysis / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D002853:Chromatography, Liquid; D005260:Female; D006801:Humans; D006929:Hyperaldosteronism / Q000097:blood* / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012083:Renin / Q000097:blood*; D053719:Tandem Mass Spectrometry; D055815:Young Adult
chemical_list: D000450:Aldosterone; D012083:Renin
keywords: Direct renin by chemiluminescence immunoassay; LC–MS/MS (liquid chromatography–mass spectrometry) aldosterone assay; Plasma aldosterone to renin ratio; Plasma renin activity; Plasma renin concentration; Primary aldosteronism