Milk Protein Allergy

Background

• Milk protein allergy is an immunologic and clinical reaction to 1 or more milk proteins.
• There are 2 types of allergic responses, each with similar prevalence:
  • immunoglobulin E (IgE)-mediated immediate hypersensitivity reaction including oral allergy syndrome, rhinoconjunctivitis, and asthma
  • non-IgE-mediated cell-mediated delayed reaction, resulting in gastrointestinal symptoms
• Most children outgrow milk protein allergy in early childhood, and non-IgE-mediated milk protein allergy generally resolves more quickly than IgE-mediated allergy.
• Exclusive breastfeeding in the first 6 months of life is associated with decreased incidence of milk protein allergy.

Evaluation

• Consider milk protein allergy in infants < 6 months old receiving cow's milk formula who present with nausea, vomiting, diarrhea, blood in stool, abdominal pain, regurgitation, atopic dermatitis, and failure to thrive.
  • Consider immunoglobulin E (IgE)-mediated immediate hypersensitivity in infants with urticaria, angioedema, wheezing, itchy eyes/nose/mouth, and swelling/irritation of the mouth, throat, or gums, usually occurring within minutes to 1 hour after ingestion of milk.
  • Consider non-IgE-mediated cell-mediated delayed reaction if symptoms occur from 1 hour to days following exposure to milk.
• For suspected IgE-mediated reactions, consider an IgE immunoassay antibody test and/or skin testing to support the diagnosis and avoid the risk of severe reaction and symptom recurrence associated with a food challenge.
• Consider further diagnostic testing consisting of:
  • replacing cow's milk formula with extensively hydrolyzed or amino acid formula in formula-fed infants, or elimination of cow's milk proteins from the mother's diet in breastfed infants
  • a food challenge, which is the gold standard for confirming the diagnosis, but carries significant risk of severe reactions and should only be performed in a clinical setting prepared to manage them

Management

• Avoid cow's milk protein until age 2-3 years. Many patients may be able to tolerate milk in baked products.
• Prescribe self-injectable epinephrine for patients at risk for severe systemic or respiratory reactions.
• Consider a referral to an allergist, pediatric gastroenterologist, and/or dietitian if severe symptoms develop.
• Consider recommending alternate sources of vitamin D and calcium in non-formula-fed patients.