Detection of cow's milk protein intolerance by an enzyme-linked immunosorbent assay

Circulating IgG antibodies to cow's milk proteins have been quantified in 182 children using an enzyme-linked immunosorbent assay (ELISA). Antibody levels in children with cow's milk protein intolerance (CMPI) were compared with those in control groups comprising other diarrhoeal diseases, atopic children, and a "normal" sample including children with toddler diarrhoea. Mean IgG antibody levels in children with CMPI were significantly higher than in any of the control groups. There were clear differences in peak antibody levels between CMPI and all other groups for each of the protein fractions tested. There was some overlap in titres between CMPI and other enteropathies but the assay gave 88% sensitivity and specificity for the diagnosis of CMPI overall and was 100% specific against the combination of non-enteropathic controls in this study. These findings indicate that the assay could be applied as an outpatient screening test for CMPI and would be particularly useful in differentiating "toddler" diarrhoea from CMPI.