N-terminal pro B-type natriuretic peptide (N-BNP) levels in cystic fibrosis patients.

Background: The diagnosis of right heart failure and pulmonary hypertension in cystic fibrosis (CF) patients with advanced pulmonary disease is sometimes difficult on clinical grounds alone. B-type natriuretic peptide (BNP) & N-terminal pro-B-type natriuretic peptide (N-BNP) levels were found to be useful in differentiating heart failure from various pulmonary diseases. However, its level was never measured in CF patients. The aim of this study was to measure N-BNP level in CF patients without heart failure.

Methods: The study included 49 patients. Of these, 32 had CF and 17 were control subjects who were matched by age and sex variables to the study group. We looked for a correlation between N-BNP and lung function test, genetic profile, height percentiles, and weight percentiles. N-BNP level was measured using an immunoassay that contains polyclonal antibodies that recognize epitopes located in the N-terminal part of proBNP.

Results: N-BNP level among CF patients without heart failure, after age and sex adjustments, was similar to the control group (Median: 47 pg/ml vs. 38 pg/ml, P = 0.248, interquartile range: 33-99 pg/ml vs. 31-76 pg/ml). A correlation between N-BNP level to age was found in both groups (CF: R = -0.398; P = 0.024, CONTROL: R = -0.054; P = 0.024). There was no correlation between N-BNP level to FEV1, O2 saturation and nutritional status. Among CF patients, eight (25%) had a mildly elevated N-BNP level whereas none was found in the control group (P = 0.038).

Conclusion: We conclude that N-BNP level among CF patients is similar to the normal population and that it has no correlation to lung function impairment. Therefore, measurement of elevated N-BNP level in CF patients might be a predictor to the development of pulmonary hypertension and heart failure.