The Basophil Activation Test in the Diagnosis of Cow's Milk Allergy in Children: A Narrative Review.

Background/Objectives: Although cow's milk allergy is the most common food allergy in infants, its diagnosis remains challenging. Conventional allergy tests, including skin-prick testing and serum-specific IgE, can support the diagnosis in cases with a clear clinical history; however, neither positive nor negative results are sufficient for a definitive diagnosis without confirmation via an oral food challenge or reintroduction. The basophil activation test has emerged as a promising adjunctive tool in the diagnosis of cow's milk allergy. Methods: We searched in the electronic databases PubMed/MEDLINE and Google Scholar for English articles published up to March 2026, using combinations of the following keywords: "cow's milk allergy," "basophil activation test, "BAT", "food allergy," "oral food challenge," "IgE-mediated," "children," and "pediatric." Results: While its widespread use is currently limited by the lack of standardized protocols, the need for fresh blood samples, and restricted availability outside specialized centers, the basophil activation test has the potential to improve diagnostic accuracy and support clinical decision-making in IgE-mediated cow's milk allergy. Importantly, basophil activation test may also reduce the number of oral food challenges by providing a safe, functional assessment of allergen reactivity, thereby minimizing patient risk and the burden of invasive testing. Conclusions: Further studies and validation are needed before the basophil activation test can be implemented as a routine diagnostic tool.