Background

Persistent tachypnea of infancy (PTI) is a form of childhood interstitial lung disease of unknown pathophysiology, associated with hyperplasia of pulmonary neuroendocrine cells (PNECs). Diagnosis is based on the characteristic clinical picture and typical radiological imaging. Lung biopsies are usually performed only in children with atypical presentations or severe courses. To date, no biochemical indicators of the disease have been identified.

Aims

We aimed to determine biomarkers that could be characteristic of PTI and support a non-invasive diagnostic approach.

Methods

Children diagnosed with PTI who were admitted for follow-up visits and healthy controls were enrolled. Concentrations of serum biomarkers secreted by PNECs (calcitonin gene-related peptide; gastrin-releasing peptide) and biomarkers of the destruction of alveolar capillary-membrane (surfactant proteins A and D; glycoprotein Krebs von den Lungen-6, KL-6; metalloproteinases 7 and 9; tissue inhibitor of metalloprotease 1) were measured.

Results

Fifty-two children with PTI and 23 healthy children were included in the study. The median age of children with PTI was 3.9 years (14 girls and 38 boys).

KL-6 levels were significantly higher in children with PTI compared to the control group (median 119.6 vs 92.1 U/ml, p=0.003), although within the normal range.

No significant differences existed between groups for the remaining biomarkers.

Conclusions

None of the investigated serum biomarkers appeared to be useful in the diagnostic approach of the PTI.