Association between C-reactive protein levels and N-terminal pro-B-type natriuretic peptide in pre-dialysis patients.
BACKGROUND
The prevalence of inflammation is high among patients with chronic renal failure but the reason of inflammation is unclear. We test the hypothesis that inflammation in chronic renal failure could be the consequence of an increased left-ventricular wall tension related to ventricular dysfunction, hypervolemia or both.


METHODS
For assessing left-ventricular filling pressure, plasma level of N-terminal pro-B-type natriuretic peptide (N-BNP) was used, as B-type natriuretic peptide is secreted from the cardiac ventricles in response to increased wall tension. N-BNP levels and C-reactive protein (CRP) were measured on the same day in 75 pre-dialysis patients. A previous history of cardiomiopathy with systolic dysfunction was present in 27 (36%) of them.


RESULTS
The levels of N-BNP were not normally distributed (mean: 2,589 +/- 4,514 pg/ml; median: 789 pg/ml). The distribution of CRP levels was also not normal (mean: 15 +/- 27 mg/l; median: 5 mg/l). Both parameters correlated significantly (r: 0.41; p < 0.005). N-BNP was higher (p < 0.001) in patients with known ventricular dysfunction. Excluding these patients, the correlation between N-BNP and CRP was stronger (r: 0.88; p < 0.001). Univariate analysis in these patients without known cardiomyopathy showed that N-BNP levels also correlated with systolic and diastolic blood pressure (r: 0.54; p < 0.005) and inversely with creatinine clearance (r: -0.43; p < 0.01), serum albumin (r: 0.6; p < 0.001) and hemoglobin levels (r: 0.37; p < 0.05). CRP levels correlated significantly (p < 0.01) with the same parameters as N-BNP in univariate analysis. However, in multiple stepwise regression analysis in which CRP was the dependent variable, only the association with N-BNP remained significant (r: 0.87; p < 0.001).


CONCLUSIONS
Our results suggest a link between left-ventricular filling pressure and inflammation in patients with advanced renal insufficiency. The importance of strict volume control in these patients, in order to reduce left-ventricular pressure and therefore inflammation, should be considered.
Ortega
Olimpia
O
Nephrology Service, Hospital Severo Ochoa, Leganés, Madrid, Spain. oortega.hsvo@salud.madrid.org
Gallar
Paloma
P
Muñoz
Mar
M
Rodríguez
Isabel
I
Carreño
Agustín
A
Ortiz
Milagros
M
Molina
Alvaro
A
Oliet
Aniana
A
Lozano
Luz
L
Vigil
Ana
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D002097:C-Reactive Protein / Q000032:analysis*; D003327:Coronary Disease / Q000150:complications; D003404:Creatinine / Q000097:blood; D048909:Diabetes Complications / Q000097:blood; D004487:Edema / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D005260:Female; D005293:Ferritins / Q000097:blood; D006352:Heart Ventricles / Q000378:metabolism; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D006973:Hypertension / Q000209:etiology; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain; D009419:Nerve Tissue Proteins / Q000097:blood* / Q000378:metabolism; D010446:Peptide Fragments / Q000097:blood* / Q000378:metabolism; D011312:Pressure; D012709:Serum Albumin / Q000032:analysis; D013318:Stroke Volume; D013599:Systole; D014657:Vasculitis / Q000097:blood / Q000209:etiology* / Q000503:physiopathology; D018487:Ventricular Dysfunction, Left / Q000097:blood / Q000150:complications* / Q000503:physiopathology
D015415:Biomarkers; D006454:Hemoglobins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D012709:Serum Albumin; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D002097:C-Reactive Protein; D005293:Ferritins; D003404:Creatinine