Utility of urinary NT-proBNP in congenital diaphragmatic hernia: a prospective pilot study.

Background: Echocardiography is the reference standard for diagnosing pulmonary hypertension (PH) and cardiac dysfunction (CD) in congenital diaphragmatic hernia (CDH). The use of an adjunct non-invasive biomarker would be invaluable. Plasma N-terminal brain Natriuretic Peptide (NT-proBNP) has been evaluated as a biomarker in CDH. Our objective was to investigate the utility of urinary NT-proBNP as an adjunct biomarker in CDH.

Methods: Prospective observational study of neonates with CDH. Urinary NT-proBNP and its ratio to urinary creatinine (UNBCR) were analyzed at 24 h of life (HOL). Spearman's correlation was used to quantify the association between the urinary NT-proBNP with corresponding plasma concentrations. Logistic regression and receiver operating characteristic (ROC) curve analyses were used to examine urinary NT-proBNP and UNBCR's association with need for ECMO. The Kruskal-Wallis test was used to compare urinary NT-proBNP concentrations with echocardiography parameters of PH and CD.

Results: Urinary NT-proBNP and UNBCR positively correlated with plasma concentrations. Patients with high right ventricular (RV) pressures had higher urinary NT-proBNP concentrations. Both urinary NT-proBNP and UNBCR concentrations increased with worsening left and right ventricular dysfunction on first postnatal echocardiogram.

Conclusion: We report the feasibility of urinary NT-proBNP as a non-invasive biomarker to assess PH and CD in CDH.

Impact statement: Non-invasive biomarkers are an important area of research in neonates as they have the potential to decrease the need for blood sampling, which may cause pain, stress, and induce iatrogenic anemia. Use of non-invasive biomarkers could be especially useful in congenital diaphragmatic hernia (CDH) who may need Extra-Corporeal Life Support (ECLS) for their management. We evaluated the potential utility of the urinary NT-proBNP in CDH. Plasma NT-proBNP has been studied in neonates with CDH; however, urinary NT-proBNP has not been explored, making this the first study to examine its potential as a biomarker.