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Cardiovascular Risk Biomarkers Cleared By Kidneys

Correct concentrations depend on proper renal function

TUESDAY, Mar. 3 (HealthDay News) -- Two biomarkers that reflect myocardial wall tension and are used to assess the risk of cardiovascular disease are cleared by the kidney, and therefore correct concentrations rely on proper renal function, researchers report in the Mar. 10 issue of the Journal of the American College of Cardiology.

Roland R.J. van Kimmenade, M.D., Ph.D., from University Hospital Maastricht in the Netherlands, and colleagues compared how B-type natriuretic peptide (BNP) and amino terminal pro-B-type natriuretic peptide (NT-proBNP) were cleared from the kidney in 165 hypertensive subjects with suspected renal artery stenosis who were undergoing renal arteriography. Peptide concentrations were measured in the renal arteries and veins, and renal plasma flow measurements and echocardiography were also performed.

The researchers found that both BNP and NT-proBNP concentrations correlated with the glomerular filtration rate. The median fractional extraction for BNP was similar for the left and right kidneys (0.21 and 0.22) as was the median fractional extraction for NT-proBNP (0.16 and 0.18). Although the fractional extractions for both peptides were strongly correlated with each other, the left and right ratios of the two fractional extractions were not associated with the glomerular filtration rate, the investigators note. Consideration of possible confounding factors confirmed the lack of independent association between fractional extraction and concentrations of both peptides, the authors report.

"That NT-proBNP and BNP are equally dependent on renal function for clearance is an advance for clinical application of these biomarkers," Suetonia C. Palmer, and A. Mark Richards, M.D., Ph.D., from the University of Otago Christchurch in New Zealand, write in an accompanying editorial.

Roche Diagnostics, which markets an NT-proBNP assay, supplied the NT-proBNP reagents for this study. Several study authors have disclosed financial or consulting relationships with Roche Diagnostics as well as Biosite, which markets a BNP assay.

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