GI - Cow’s Milk Protein Allergy

Question 1

Definition

Answer 1

Cow’s milk protein allergy (CMPA) is an adverse Type 1 hypersensitivity immune reaction to the proteins found in cow’s milk

Question 2

Epidemiology

Answer 2

First 3 months of life in formula fed infants
- rarely seen in exclusively breastfed infants

Question 3

Aetiology

Answer 3

There are two main types of proteins in cow’s milk that can cause allergic reactions:
1) Casein: Casein is the primary protein in cow’s milk, accounting for about 80% of its total
protein content. It is a common allergen in CMPA.
2) Whey: Whey proteins make up the remaining 20% of the protein content in cow’s milk.
They can also cause allergic reactions in individuals with CMPA

Question 4

Risk factors

Answer 4

FHx of allergies,
PHx of allergies,
Early introduction to cow milk

Question 5

Pathophysiology

Answer 5

Immediate hypersensitivity reaction:
1. This type of reaction occurs within minutes to a few hours after ingesting cow’s milk proteins.
2. It is mediated by immunoglobulin E (IgE) antibodies, which are produced by the immune system in response to specific proteins in cow’s milk.
3. The IgE antibodies recognize the cow’s milk proteins as foreign and bind to mast cells and
basophils, which are immune cells that release histamine and other inflammatory mediators.
4. The release of these mediators leads to the typical symptoms of an immediate allergic reaction, such as hives, swelling, gastrointestinal disturbances, and respiratory symptoms.

Delayed hypersensitivity reaction:
● In some cases of CMPA, the allergic reaction may be delayed and occur several hours to days after consuming cow’s milk proteins.
● This type of reaction is mediated by other components of the immune system, including T cells. When T cells recognize cow’s milk proteins as foreign, they release inflammatory cytokines, which contribute to the development of inflammation and tissue damage.
● The delayed reaction can result in gastrointestinal symptoms, such as chronic diarrhoea, vomiting, and blood in the stool, as well as skin manifestations like
eczema.

Question 6

Symptoms

Answer 6

● Regurgitation and vomiting
● Diarrhoea
● Urticaria, atopic eczema
● ‘Colic’ symptoms: irritability, crying
● Wheeze, chronic cough
● Rarely angioedema and anaphylaxis may occur
● Failure to thrive

Question 7

Diagnosis

Answer 7

Clinical (e.g. improvement with cow’s milk protein elimination). Ix include
● Skin prick/patch testing
● Total IgE and specific IgE (RAST) for cow’s milk protein = known IgE mediated so this test is not done tbh

Question 8

DDx

Answer 8

Lactose intolerant
GI disorders

Question 9

Treatment

Answer 9

If the symptoms are severe (e.g. failure to thrive) refer to a paediatrician.

Management if formula-fed:
- FIRST LINE = Extensive Hydrolysed Formula (eHF) milk replacement formula with mild to
moderate symptoms
- 2nd line- Amino acid formula (AAF) in infants with severe CMPA or if no response to eHF

Management if breastfed:
- Continue breastfeeding
- Eliminate cow’s milk protein form maternal diet
= Consider prescribing calcium supplements for breastfeeding mothers
- Use eHF milk when breastfeeding stops, until 12 months of age and at least for 6 months

Question 10

Complications

Answer 10

Nutritional deficiencies
FTT
Eczema
Skin complications
Anaphylaxis (RARE)