The rechallenge step is crucial to an accurate diagnosis, but getting parents to follow through can be difficult

Can you tell the difference between lactose intolerance or a cow’s milk protein allergy in infants?

Dr Rupert Hinds, a consultant gastroenterologist at Monash Children’s Hospital, and senior allergy dietitian, Dr Vicky McWilliam in the Department of Allergy and Immunology at The Royal Children’s Hospital in Melbourne, talk us through the differences between the two, how to manage Cow’s Milk Protein Allergy (CMPA) in infants and the diagnosis and management challenges.

It may be hard to find a GP who hasn’t seen parents in their surgery with a baby who has gut issues. Often, they’ll think cow’s milk or a lactose intolerance may be the culprit.

Paediatric gastroenterologist Dr Rupert Hinds says it’s hard to miss the allergies that cause rashes or hives immediately after eating, but it’s a different story for the non-IgE mediated allergies in infants.

There’s a spectrum of symptoms they can present with, ranging from reflux to runny stool with blood—but separating the physiological symptoms from the allergic ones “can be tricky,” he says.

Diagnosing through exclusion and rechallenge

“I think the challenge, of particularly the non-IgE mediated types of cow’s milk allergy, is that it can be dressed up as a lot of different conditions. So, it’s hard to unpack what may be reflux, what may be some other type of gastrointestinal condition, and what is food allergy… and there are no diagnostic tools for this type of allergy either.”

“So, it’s taking the food out on the baby side or the breastfeeding mum’s side, seeing if the symptoms go away, and then re-challenging.”

Non-IgE mediated vs IgE mediated cow’s milk allergies

Taking a good history is vital, especially when it comes to family and personal history of allergies.

Dietitian Dr Vicky McWilliam says you’re essentially building a story, and using the timing of the reaction to tell whether it’s IgE mediated or non-IgE mediated.

“So, reactions that are happening within half-an-hour to an hour, and mainly the skin with hives or angioedema, and immediate vomiting— they would be proof that you’re dealing with an IgE mediated food allergy.”

“Whereas a baby that’s presenting with … essentially gastrointestinal symptoms, and they’re more delayed and vague in nature, they would be leading you down the pathway of thinking about a non-IgE mediated cow’s milk allergy.”

She says it’s important to ask about timing of reactions, what the reactions look like, how much of the food was eaten, what the family feels the triggers are, and whether the symptoms change when the formula is changed.

Is it lactose intolerance or a non-IgE mediated CMPA?

The next challenge is determining if it’s a lactose intolerance or a non-IgE mediated CMPA.

Dr Hinds says “to be absolutely clear, to have a primary lactose intolerance as a baby is extraordinarily rare. It’s very, very rare indeed … an almost never event.”

Despite this, a lactose-free formula is often recommended, but it often fails as the still cow’s milk protein present.

Dr McWilliam says this can create challenges when it comes to re-introducing foods as parents have become wedded to their initial diagnosis, even though it was incorrect.

“The most important step in the diagnosis of non-IgE mediated cow’s milk allergy is probably the rechallenge step. So, if you’re trying to work out if symptoms are related to particularly cow’s milk protein, when symptoms resolve it’s very difficult for parents, and clinicians sometimes, to then ask the family to retry that particular food back in the diet and bring the symptoms back to confirm the diagnosis.”

As vital as it is for diagnosis “that’s a step that gets missed and then people have stuck on a journey or the limited diet for longer than they probably need to be or unnecessarily.”

Choosing a formula

Picking the right formula is another challenge. Dr McWilliam says there are now a lot of choices but for a mild proctocolitis “a plant based infant formula that families can access over-the-counter would be completely suitable.”

But if there are issues with growth or malabsorption symptoms, “then I think, a scripted formula that has either a single amino acid base or a broken-down cow’s milk protein is what we need to use.”

Another area of confusion is the role of probiotics, prebiotics and symbiotics (a combination of the two) in formulas and in their long-term impact on allergies. Do they provide long term benefits? Hinds has his doubts. He says we have studies that show the probiotics are there in the child’s pooh, but “we don’t really have the studies that have looked that long term to be able to give us that answer.”

To hear more about this topic, listen to the podcast Professor Hinds and Dr McWilliam recorded for Healthed here.