Serum eosinophil-derived neurotoxin: a new promising biomarker for cow's milk allergy diagnosis.

Abstract

Cow's Milk Allergy (CMA) diagnosis is often a challenge due to the non-specific nature of symptoms and lack of a confirmatory diagnostic test. To our knowledge no previous studies investigated serum Eosinophil-Derived Neurotoxin (sEDN) in CMA. So, we aimed to assess the role of sEDN in CMA diagnosis. Forty-five infants with CMA were compared to 45 infants with functional gastrointestinal disorders (FGIDs) and 45 healthy controls. For all participants, Cow's Milk-related Symptom Score (CoMiSS) was documented, and sEDN level with hematological parameters were measured before starting elimination diet. Receiver operation characteristic (ROC) curve identified sEDN > 14 ng/mL and CoMiSS > 9 as the optimal cut-off points to discriminate CMA from other groups with sensitivity 86.67%, 97.78% and specificity 60.00%, 78.89% respectively. Additionally, absolute neutrophil count (ANC) showed the highest sensitivity and specificity (80.0% and 78.89%) among hematological parameters. Although CoMiSS and ANC showed a significant positive correlation with sEDN in CMA group, CoMiSS was the only significant predictor for sEDN in multivariate linear regression. sEDN showed high sensitivity in discriminating infants with and without CMA. Therefore, it is suggested as a potential biomarker for CMA diagnosis. Also, ANC should be closely monitored in these infants. CMA presents with high heterogeneity, which complicates the diagnosis especially non-IgE-mediated and mixed types. So, oral food challenge continues to be the gold standard for its diagnosis. ROC curve identified CoMiSS > 9 as the best cut-off point to identify CMA. However, CoMiSS is a good awareness tool for CMA but not a diagnostic tool. sEDN level was significantly higher in infants with CMA with a good diagnostic performance in differentiating them than those without CMA. So, it is suggested as a potential biomarker for CMA diagnosis. ANC could have a role in CMA diagnosis and differentiating it from FGIDs.