Non-cardiac determinants of NT-proBNP levels in the elderly: relevance of haematocrit and hepatic steatosis.
BACKGROUND
The levels of B-type natriuretic peptide (BNP), a marker of heart failure, are higher in women and anaemic subjects, and tend to be lower in obese people. These relationships are still largely unexplained and it is unclear whether they also apply to the N-terminal portion of BNP precursor (NT-proBNP).


OBJECTIVE
This cross-sectional study was performed to assess general and abdominal obesity, sex and other variables as possible extra-cardiac determinants of NT-proBNP.


RESULTS
A random sample of 713 subjects aged 65-74 years resident of Pianoro (Northern Italy) underwent assessment of NT-proBNP, several haemato-chemical variables, body mass index (BMI), body fat estimation (through skinfold measurement), waist circumference, intra-abdominal thickness and possible presence of hepatic steatosis (by ultrasound examination). An echocardiogram was performed in a subset of 125 subjects. In multivariable analysis NT-proBNP was inversely associated with haematocrit (r=0.22, P<0.0001) and hepatic steatosis (r=0.13, P=0.0001), while no association was found with BMI and body fat estimation. NT-proBNP was higher in women, but this relationship disappeared when haematocrit was included in the multivariable model. The associations with haematocrit and hepatic steatosis were independent from echocardiographic measurements.


CONCLUSIONS
NT-proBNP is increased in subjects with low haematocrit, which explains the higher values in women. Although NT-proBNP is not affected by general adiposity, low levels of NT-proBNP are associated with hepatic steatosis.
Muscari
Antonio
A
Department of Internal Medicine, Cardioangiology, Hepatology, University of Bologna, S. Orsola-Malpighi Hospital, Via Albertoni, 15, 40138 Bologna, Italy. amuscari@med.unibo.it
Berzigotti
Annalisa
A
Bianchi
Giampaolo
G
Giannoni
Claudia
C
Ligabue
Amedeo
A
Magalotti
Donatella
D
Sbano
Dario
D
Zacchini
Annalisa
A
Zoli
Marco
M
D000368:Aged; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000097:blood; D005234:Fatty Liver / Q000097:blood* / Q000503:physiopathology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006400:Hematocrit; D006801:Humans; D006973:Hypertension / Q000097:blood; D008297:Male; D015999:Multivariate Analysis; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D009765:Obesity / Q000097:blood* / Q000503:physiopathology; D010446:Peptide Fragments / Q000097:blood*; D018570:Risk Assessment; D012737:Sex Factors; D012907:Smoking / Q000097:blood
D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain