ED: Allergies to cow’s milk protein can present with various clinical manifestations in babies, which are important to differentiate.
Affecting at least 2% of infants under age two, Cow’s Milk Protein Allergy (CPMA) may be more common due to increased real and perceived food allergy. Usually presenting within the first six months of life it appears in formula-fed and fully breast-fed infants (due to maternal dairy intake).
CMPA is defined as an immunologically (IgE or non IgE mediated) adverse reaction to cow’s milk protein (CMP). The major dairy allergens are casein and/or whey proteins. Cross reactivity exists with all other mammal milks and soy milk to a lesser degree.
Accurate diagnosis is vital. Diagnostic delay may put children at risk of either acute allergic reactions or inappropriate dietary manipulations.
Immediate allergic reactions (IgE mediated) cause urticaria, erythema, angio-oedema or vomiting in up to two hours after ingestion of dairy products; anaphylaxis is a severe immediate reaction with respiratory tract involvement (coughing, wheezing, stridor) and/or hypotension. Symptoms in infants are often harder to recognise and can include severe irritability, pallor and floppiness. All affected children need to avoid CMP with provision of an appropriate substitute, an allergy action plan and, if at risk of anaphylaxis, an adrenaline auto injector. Breastfeeding mothers may have to avoid dairy in their own diet. Fortunately, most but not all children will outgrow CMPA.
Non IgE-mediated conditions: Food protein induced enterocolitis syndrome typically presents with acute onset of repeated vomiting and sometimes diarrhoea leading to dehydration, hypotonia and pallor one to three hours after ingestion. Symptoms can be mistaken for gastroenteritis, sepsis or other gut disorders. Multiple presentations before the diagnosis is established are not uncommon. Acute management involves rehydration. Affected infants need to avoid all CMP. The condition often resolves before school age.
Infants with allergic proctocolitis are usually well babies presenting with low-grade rectal bleeding without other features. CMP avoidance is usually required only in the first year of life as the condition resolves.
Symptoms of eosinophilic oesophagitis can occur within hours to days and include food refusal, difficulty feeding, poor weight gain and dysphagia. Endoscopy might be required to confirm the diagnosis followed by a CMP-free diet.
Infants with CMP-induced enteropathy may present with diarrhoea, failure to thrive, vomiting possibly leading to hypoproteinaemia and anaemia. Onset of symptoms can be hours to days after dairy ingestion. Complete CMP avoidance is required.
Role of intolerance
An intolerance to CMP can play a role in other conditions such as eczema, gastro-oesophageal reflux, infantile colic and constipation. A carefully guided trial of (sometimes partial) eliminating dairy protein from the diet can be useful, perhaps where there is doubt, followed by a CMP challenge.
Key messages
- Cow’s Milk Protein Allergy has various clinical manifestations
- Accurate diagnosis is important as treatment is condition-specific
- Most but not all children will outgrow this allergy
Further reading: see position papers ASCIA https://www.allergy.org.au/health-professionals/papers
References available on request.
Questions? Contact the editor.
Author competing interests: nil relevant disclosures.
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