Altered sodium intake affects plasma concentrations of BNP but not proBNP in healthy individuals and patients with compensated heart failure.
OBJECTIVE
Plasma B-type natriuretic peptide (BNP) and proBNP are promising markers for treatment of heart failure (HF), but the intra-individual biological variation is high. We investigated whether changes in sodium intake and posture contribute to this variation.


RESULTS
A total of 12 healthy individuals and 12 patients with medically treated compensated HF were examined after 1 week of low (70 mmol [1.61 g] per day) and 1 week of high (250 mmol [5.75 g] per day) sodium intake. Plasma volume and plasma concentrations of BNP and proBNP were determined after 1 h in seated and 1 h in supine position. In healthy individuals, the plasma BNP concentration increased significantly on high sodium intake with a ratio (high sodium/low sodium) of 2.00 (1.32-3.03, P = 0.004). The corresponding values for HF patients were 1.69 (1.25-2.29, P = 0.003). The plasma BNP concentration changed modestly by a posture change, with a plasma BNP ratio (supine/seated) of 1.15 (1.07-1.14, P = 0.001) and 1.06 (0.99-1.24, P = 0.088) in healthy subjects and HF patients, respectively. Plasma proBNP concentrations were neither significantly affected by posture nor by sodium intake.


CONCLUSIONS
Sodium intake has a considerable effect on plasma BNP and therefore contributes to the intra-individual variability. We suggest dietary sodium intake to be standardized at least 3 days prior to blood sampling for the determination of plasma BNP.
Damgaard
Morten
M
Division of Aviation Medicine, Medical Department B, Rigshospitalet, Copenhagen DK-2100, Denmark. mdamgaard@dadlnet.dk <mdamgaard@dadlnet.dk>
Goetze
Jens Peter
JP
Norsk
Peter
P
Gadsbøll
Niels
N
D015415:Biomarkers / Q000378:metabolism; D018592:Cross-Over Studies; D006333:Heart Failure / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D010953:Plasma Volume / Q000502:physiology; D011187:Posture; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage* / Q000494:pharmacology
D015415:Biomarkers; D010446:Peptide Fragments; D017673:Sodium Chloride, Dietary; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain