The only method to confirm or refute a non-IgE CMPA diagnosis is a two to four week dairy elimination diet, ALWAYS to be followed by a re-challenge (reintroduction of dairy in the diet). Any other allergy testing will not aid diagnosis.
If the baby is breastfed or combination fed, the Mother will need to eliminate all dairy from her own diet during the trial period. This may require dietitian support and the GP should prescribe Mum 1000mg calcium and 10 micrograms vitamin D daily. It is important to support the Mum to continue breastfeeding. BREASTFEEDING SHOULD NOT BE INTERRUPTED AND CAN BE CONTINUED SAFELY FROM DAY 1 OF THE DAIRY ELIMINATION TRIAL.
The GP Infant Feeding Network has useful advice on how to manage this plus links to support sites for parents: https://gpifn.org.uk/imap/
If complete elimination of cow’s milk protein from the maternal diet does not help an exclusively breastfed baby, then non-IgE cow’s milk allergy can be ruled out and all dairy kept in the diet.
If the baby is combination-fed or formula fed, an extensively hydrolysed formula (EHF) should be tried during the elimination trial. Then, the Mum should reintroduce all dairy in her own diet first (while baby continues on the EHF) to check whether baby tolerates the tiny amount of cow’s milk protein going into the breast milk. (If tolerated, a maternal dairy elimination is no longer needed. If the baby becomes symptomatic again, ongoing maternal dairy elimination is needed). Then advise parents to reintroduce their usual cow’s milk infant formula in order to confirm/refute the diagnosis and establish if the baby needs to remain on an EHF.
Please refer to primary care prescribing guidelines to select an appropriate extensively hydrolysed formula: https://www.kingstonformulary.nhs.uk/page/33/9-nutrition-and-blood-guidelines
Babies up to 3-4 months usually readily accept the formula change in taste, but if not, advise the parent to gradually transfer over few days, by mixing increasingly smaller amounts of their usual formula or breast milk into the extensively hydrolysed formula. Babies who are being weaned onto solid foods around 6 months of age will need to be weaned dairy free. All this requires dietetic support. In the meantime, use the following useful resource: https://www.allergyuk.org/assets/000/001/207/Cow’s_Milk_Free_Diet_Information_for_Babies_and_Children_original.pdf?1501228993
Reassure parents that almost all children will outgrow a non-IgE mediated cow’s milk allergy. Once the baby is a year of age, the dietitian will guide them on how to do reintroduce dairy into the diet gradually using the “milk ladder”.
• a non-IgE CMPA is NOT the same thing as lactose intolerance (very rare in infants). Lactose is a sugar, broken down by enzymes in the gut, whereas an allergy involves an immune reaction to a protein – therefore prescribing a lactose-free formula will not help.
• A goat’s milk formula is of no use either (as the proteins are ~90% similar to the cow’s) and should not be advised.