title: Short- and long-term individual variation in NT-proBNP levels in patients with stable coronary artery disease.
abstract: BACKGROUND
  In addition to diagnosis of heart failure (HF) natriuretic peptides (BNP and NT-proBNP) may be used for risk prediction in stable and acute coronary artery disease. The aim of the study was to evaluate the short- and long-term individual variation of NT-proBNP in patients with stable coronary artery disease.
  
  
  METHODS
  Twenty-four patients with suspected stable coronary artery disease and scheduled for elective coronary angiography were included. Blood samples were drawn at enrolment and, on average 3 weeks later, serially the day prior to coronary angiography. NT-proBNP was determined using Elecsys proBNP sandwich immunoassay (Roche Diagnostics).
  
  
  RESULTS
  The individual variation in NT-proBNP over 4h was 11.8%, over 20 h 12.4% and over 3 weeks 20.4%. The corresponding positive and negative lognormal reference change values (RCV) were +41/-29%, +42/-30% and +76/-43%, respectively. No significant circadian variation was found.
  
  
  CONCLUSIONS
  Our results suggest that an increase in NT-proBNP levels of >42% or a decrease of >30% is needed to indicate a reliable short-term change; and for a long-term change an increase of >76% or a decrease of >43% is required. This should be considered when interpreting changes in NT-proBNP levels.
authors.affiliation: Department of Cardiology, Örebro University Hospital, Örebro, Sweden. anna.nordenskjold@orebroll.se
authors.forename: Anna M
authors.initials: AM
authors.lastname: Nordenskjöld
authors.forename: Håkan
authors.initials: H
authors.lastname: Ahlström
authors.forename: Kai M
authors.initials: KM
authors.lastname: Eggers
authors.forename: Ole
authors.initials: O
authors.lastname: Fröbert
authors.forename: Per
authors.initials: P
authors.lastname: Venge
authors.forename: Bertil
authors.initials: B
authors.lastname: Lindahl
mesh_terms: D000328:Adult; D000368:Aged; D003324:Coronary Artery Disease / Q000097:blood* / Q000175:diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain