[Quality assurance in diagnostics: are there normal values for IgG-antibodies to cow's milk proteins?].
BACKGROUND: The value of IgG-cow's milk antibodies is heavily disputed. Therefore, aim of the study was to establish normal values for these IgG-antibodies and to determine their diagnostic significance especially for gastrointestinal allergic manifestations. PATIENTS AND METHODS: 702 newborns were included prospectively. They received different feedings: mothers milk, cow's milk based formula and a partially or an extensively hydrolyzed formula. All children were examined annually or on occasion of allergic manifestations. An indirect immunofluorescent test was used for the assessment of IgG-antibodies against casein, beta-lactoglobulin, alpha-lactalbumin and bovine serum albumin. Values were expressed as geometric mean titers. RESULTS: IgG-antibody titers rose slowly in the exclusively breast-fed children and peaked rapidly in the cow's milk formula-fed group, especially during the first year of life. There were no significant differences between children with and without allergic manifestations. Because of a large overlap between asymptomatic and symptomatic children it was impossible to establish normal values for the IgG-cow's milk antibodies. CONCLUSIONS: The occurrence of IgG-cow's milk antibodies is a physiologic phenomenon without diagnostic significance. The costs of these determinations can be saved to improve process quality.