Difficulties in diagnosing non-IgE-dependent gastrointestinal forms of food allergy: How informative is fecal calprotectin?

Abstract

The prevalence of allergic diseases is increasing at rates corresponding to epidemic’s spread rates. Cow’s milk protein allergy (CMPA) is one of the most common food allergies in infancy. Its clinical variants remain hard-to-diagnose diseases due to their multiple clinical faces. Food allergy can develop along the pathway associated with both IgE and non-IgE, or mixed one. Non-IgEassociated variants of food allergies, due to the lack of accurate and specific laboratory markers, can cause significant difficulties in making a diagnosis. The search for new diagnostic markers continues. Faecal calprotectin, a calcium-binding leukocyte protein consisting of a complex of two monomers S100A8 and S100A9, may be one of them. Faecal calprotectin concentration is directly proportional to the number of leukocytes migrating into the intestinal wall, due to which faecal calprotectin becomes an accurate, non-invasive and sensitive indicator reflecting the level of inflammation in the intestines. Today, serum and faecal calprotectin are used as laboratory markers, and the latter, being more accessible and not critical for collection material is widely known as a diagnostic marker of inflammatory bowel diseases. Some studies suggest that faecal calprotectin may be used to diagnose cow’s milk protein allergy in young infants when other diagnostic tests are not available. Data from various studies remain contradictory. Further studies to investigate the possibilities of using faecal calprotectin as a marker of the gastrointestinal food allergy in young children is needed.