Abstract 12041: Cystatin C and Body Surface Area Are Major Determinants of the Ratio of N-Terminal Pro-Brain Natriuretic Peptide to Brain Natriuretic Peptide Levels in Pediatric Patients
Background: Although the N-terminal pro-BNP (NT)/BNP ratio in children decreases with increasing age, factors contributing to it remain unclear. While NT clearance occurs only in the kidney, BNP clearance occurs in the kidney, liver, lung, and vascular endothelium. Because of the equimolar production of NT and BNP, NT/BNP depends on the clearance rate of each. The maturation of renal function and changes in other organs may contribute to the age-related decrease of NT/BNP. The maturation factor may be better represented by age or body size. Thus, this study tested the hypothesis that NT/BNP may be independently related to Cystatin C (CysC), a GFR marker, taking into account diastolic function, age, or BSA in children.
Methods: The study included 433 pediatric heart disease patients (age, ≤20 years; mean age, 5.3±4.9 years) who underwent cardiac catheterization and simultaneous measurements of BNP, NT, and CysC. Pulmonary capillary wedge pressure (PCWP) was used as a marker of ventricular diastolic stretch. Variables showing skewed distribution were transformed into common logarithm.
Results: Data distributions were log BNP (0.6-3.4), log NT (0.8-4.2), PCWP (2-24 mmHg), and CysC (0.59-1.88 mg/L). Log NT/BNP (Figure) was affected by PCWP (β = –0.18) and log CysC (β = 0.59). When age and log BSA were added to stepwise regression, age was not adopted (p = 0.21) because of multicollinearity to log BSA, but log CysC and log BSA were independent factors of log NT/BNP; PCWP (β = –0.10), log CysC (β = 0.22), and log BSA (β = –0.66, all VIF ≤ 1.5).
Conclusion: Renal dysfunction independently increased NT/BNP, while high BSA decreased it, as the greatest determinant of NT/BNP in children. Moreover, the observation that high PCWP decreased NT/BNP may suggest that worsening heart failure may slow the clearance of BNP from other organs, which may serve as a compensatory pathway of heart failure. These factors need to be considered for the assessment of BNP and NT.
- © 2013 by American Heart Association, Inc.