Diagnosis of cow's milk allergy in children: determining the gold standard?

Abstract

Cow's milk protein allergy (CMPA) affect many organs, from mouth to gut, with, immediate and delayed reactions, including infantile colic, food protein induced enterocolitis syndrome, enteropathy, eosinophilic disorders, among which infantile proctocolitis, and “dysmotility” disturbances, gastro-esophageal reflux and constipation. Diagnosis follows usual steps, careful history taking and medical examination, before starting an elimination diet, for diagnosis and treatment. Beyond, laboratory tests may help, but definitive conclusion will arise from the oral food challenge. The double-blind-placebo-controlled-food challenge, the “gold standard”, is needed in clinical research. The food challenge includes the progressive at-home reintroduction of milk, all the more needed since most cases of CMPA in infants are delayed: in clinical practice, diagnosing CMPA is more than saying if the child reacts to cow's milk. One has to define the syndrome the child is suffering from, the risk implied, the best replacement formula. When tolerance develops, a second diagnostic procedure allows seeing if the child has outgrown his disease and, if not, what is the expected outcome and which type of food is best adapted: small amounts of milk, or transformed forms, such as baked milk. Primary care practice is adapted to non-IgE mediated CMPA. When CMPA is part of multiple food allergies or of an eosinophilic disorder, referral centers will perform multiple allergy testing, endoscopic procedures and complex dietary guidance.

Keywords::

• allergy
• cow's milk
• diagnosis
• oral food challenge
• skin prick tests
• specific IgE

Financial & competing interests disclosure

C Dupont has been a consultant for Sodilac, France. The author has received honoraria from Nestlé, Danone, Mead Johnson, Pfizer and United Pharmaceuticals. The author also has stock options or ownership for DBV Technologies, Bagneux, France. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• For the initial diagnosis of cow's milk protein allergy, the first step is, in the presence of suggestive symptoms, the elimination diet that serves both as a diagnostic and as a treatment.

• The oral food challenge (OFC) is the second step performed within 2–4 weeks of elimination diet, following skin and specific IgE testing to better evaluate the risk of the OFC.

• Skin and specific IgE testing may help avoiding the OFC, but only if values are clear-cut. OFCs are essential in all other medical settings, which constitute more or less a gray zone. This gray zone encompasses IgE and non-IgE-mediated allergy.

• Diagnosing cow's milk protein allergy in a child is also diagnosing which type of syndrome the child is suffering from, in order to better evaluate the risks, the prognosis and the best adapted feeding.

• When the child is supposed to have outgrown his disease, a second diagnostic period allows detecting persistent cases, measuring the reactivity to milk of the child and adapting his diet, using milk in small quantities, baked or probably also in some fermented forms.