title: High-Sensitivity Sandwich ELISA for Plasma NT-proUcn2: Plasma Concentrations and Relationship to Mortality in Heart Failure.
abstract: Urocortin 2 (Ucn2) has powerful hemodynamic, renal, and neurohormonal actions and likely participates in normal circulatory homeostasis and the compensatory response to heart failure (HF). A validated assay for endogenous circulating Ucn2 would facilitate investigations into Ucn2 physiology and elucidate its derangement and potential as a biomarker in heart disease.
  
  
  
  We developed a chemiluminescence-based sandwich ELISA to measure plasma N-terminal (NT)-proUcn2 in non-HF patients (control; n = 160) and HF patients with reduced (HFREF; n = 134) and preserved (HFPEF; n = 121) left ventricular ejection fraction (LVEF).
  
  
  
  The ELISA had a limit of detection of 8.47 ng/L (1.52 pmol/L) and working range of 23.8-572 ng/L. Intra- and interassay CV and total error were 4.8, 16.2, and 17.7%, respectively. The median (interquartile range) plasma NT-proUcn2 concentration in controls was 112 (86-132) ng/L. HFREF, HFPEF, and all HF plasma concentrations were significantly increased [117 (98-141) ng/L, P = 0.0007; 119 (93-136) ng/L, P = 0.0376, and 119 (97-140) ng/L, P = 0.001] compared with controls but did not differ significantly between HFREF and HFPEF. NT-proUcn2 was modestly related to age (r = 0.264, P = 0.001) and cardiac troponin T (r = 0.258, P = 0.001) but not N-terminal pro-B-type natriuretic peptide, body mass index, LVEF, or estimated glomerular filtration rate. On multivariate analysis, plasma NT-proUcn2 was independently and inversely related to 2-year mortality in HF.
  
  
  
  The validated ELISA measured human NT-proUcn2 in plasma and showed modest but significant increases in HF patients compared with controls. In HF, the unusual inverse relationship between plasma NT-proUcn2 and 2-year mortality portends potential prognostic value but requires further corroboration.
authors.affiliation: Cardiovascular Research Institute, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore;
authors.forename: Oi Wah
authors.initials: OW
authors.lastname: Liew
authors.affiliation: Christchurch Heart Institute, University of Otago, Otago, New Zealand.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Yandle
authors.affiliation: Cardiovascular Research Institute, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore;
authors.forename: Jenny P C
authors.initials: JP
authors.lastname: Chong
authors.affiliation: Cardiovascular Research Institute, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore;
authors.forename: Yan Xia
authors.initials: YX
authors.lastname: Ng
authors.affiliation: Christchurch Heart Institute, University of Otago, Otago, New Zealand.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Frampton
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore;
authors.forename: Tze Pin
authors.initials: TP
authors.lastname: Ng
authors.affiliation: Cardiovascular Research Institute, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore;
authors.forename: Carolyn S P
authors.initials: CS
authors.lastname: Lam
authors.affiliation: Cardiovascular Research Institute, Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore; Christchurch Heart Institute, University of Otago, Otago, New Zealand. mdcarthu@nus.edu.sg.
authors.forename: A Mark
authors.initials: AM
authors.lastname: Richards
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000175:diagnosis / Q000401:mortality*; D006801:Humans; D049449:Luminescence; D008297:Male; D008875:Middle Aged; D054832:Urocortins / Q000097:blood*
chemical_list: D015415:Biomarkers; C426705:UCN2 protein, human; D054832:Urocortins; D003346:Corticotropin-Releasing Hormone