title: Reference intervals and decision limits for B-type natriuretic peptide (BNP) and its precursor (Nt-proBNP) in the elderly.
abstract: BACKGROUND
  Elderly patients have the highest prevalence of heart failure (HF). The aims of the study were to establish a reference interval for B-type natriuretic peptide (BNP) and (Nt-proBNP) in elderly people, and to identify clinically relevant decision limits based on long-term outcome.
  
  
  METHODS
  Plasma concentrations of BNP and Nt-proBNP were measured from two elderly populations: 218 healthy subjects (mean age 73 years, population I), and 474 patients (mean age 73 years, population II) with symptoms associated with HF. Study population II was followed for 6 years with registration of all cardiovascular mortality.
  
  
  RESULTS
  An association between both BNP and Nt-proBNP concentrations and age was found. The upper limit for the reference intervals in the healthy elderly (population I) was: BNP< or =28 pmol/L (< or =97 ng/L), and Nt-proBNP< or =64 pmol/L (< or =540 ng/L). Based on cardiovascular mortality, decision limits for BNP (approximately 50 pmol/L, approximately 170 ng/L) and Nt-proBNP ( approximately 200 pmol/L, approximately 1700 ng/L) (population II) were determined.
  
  
  CONCLUSIONS
  Besides establishing reference intervals for BNP and Nt-proBNP in an elderly population, a higher clinically relevant decision limit for BNP and Nt-proBNP was identified, indicating additive prognostic information of the peptides on top of measurements by echocardiography. Therefore, both reference intervals and decision limits should be included in clinical practice.
authors: Department of Cardiology, University Hospital of Linköping, Linköping, Sweden. urban.alehagen@ihs.liu.se
authors: Urban
authors: U
authors: Alehagen
authors: Jens Peter
authors: JP
authors: Goetze
authors: Ulf
authors: U
authors: Dahlström
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D012016:Reference Values
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain