Cows milk protein allergy Flashcards
What is cows milk protein allergy?
Immune mediated allergic response to naturally occurring proteins caseins and whey in cows milk
How is cows milk protein allergy classified?
IgE mediated
Non-IgE mediated
Mixed
How common is cows milk protein allergy?
7% of formula or mixed fed infants
0.5% exclusively breast fed infants
What is a protective factor for cows milk protein allergy?
Breastfeeding
Describe IgE mediated cows milk protein allergy
A type 1 hypersensitivity reaction
CD4 TH2 cells stimulate B cells to produce IgE antibodies against cows milk protein which trigger release of histamine and other cytokines from mast cells and basophils
Describe non-IgE mediated cows milk protein allergy
Involves T activation against cows milk protein
What are the risk factors for cows milk protein allergy?
Personal or family history of atopy
How are symptoms of cows milk protein allergy classified?
Speed of onset after exposure GI Skin Resp Aetiology of the allergy
Describe the clinical presentation of IgE mediated cows milk protein allergy
Acute and frequently rapid onset - within 2 hours of exposure
Skin - pruitis, erythema, acute urticaria (localised or generalised), acute angio-oedema (lips, face, eyes)
GI - Oral pruitis, nausea, colicky abdo pain, vomiting and diarrhoea
Resp - lower (cough, chest tightness, wheeze or SOB) and upper (nasal itching, sneezing, rhinorrhoea, congestion)
Describe the clinical presentation of non-IgE mediated cows milk protein allergy
Non-acute and generally delayed - manifest after 48hours to 1 week after ingestion
Skin - pruitis, erythema, atopic eczema
GI - GORD, loose or frequent stools, Blood/mucus in stool, abdo pain, infantile colic, food refusal/aversion, constipation, perianal redness, faltering growth in conjunction with GI symptoms
Resp - Lower (cough, tight chest, wheeze, SOB)
List the questions needed to be asked in an allergy focused history for CMPA
Personal and family history of atopy Diet and feeding history of infant Diet and milk ingestion of the mother if breast feeding Any previous management for symptoms Which milk/foods Age of onset Speed of onset following exposure Duration Frequency and severity Settling of reaction Reproducibility of symptoms
What examination is required for CMPA?
GI
Look for malnutrition signs
Growth charts
Signs of atopic conditions - asthma, eczema, allergic rhinitis
List some differentials of CMPA
Food intolerance Allergic reaction to food Anatomical abnormalities - Meckel's diverticulum Chronic GI disease Pancreatic insufficiency UTI
How is CMPA diagnosed?
Non-IgE mediated - clinically
IgE mediated - RAST test
Haematinics useful to diagnose iron deficiency
Describe the RAST test
Radioallergosorbent test - detects IgE antibodies to cows milk allergy
Describe the usefulness of the RAST test
Very sensitive but not very specific
High false positive rate
How is cows milk protein allergy managed?
Avoidance of cows milk in all forms including mothers breastmilk - elimination diet for 6 months or until infant is 9-12 months with re-evaluation every 6-12 months to assess for tolerance of cows milk protein
Nutritional counselling
Monitoring of growth
Replacement of formula milk
Which guideline ladder may be helpful for patients with CMPA?
MAP milk ladder
Which two milks can formula milk be replaced with in CMPA?
Extensively hydrolysed formula
Amino acid formula
Describe the extensively hydrolysed formula
Cheaper, first line formula made with cows milk but with casein and whey broken down into smaller peptides which are less immunogenic
What percentage of patients will respond to extensively hydrolysed formula?
90%
Describe amino acid formula
Used for the 10% who do not respond to extensively hydrolysed formula or who have very severe symptoms
More expensive
2nd line
Why are soya based formulas not recommended in infants <6mo?
Weak oestrogenic effects of isoflavones and absorption of minerals and trace elements may be inhibited by phytate found in this milk
What are the complications of cows milk protein allergy?
Malabsorption
Reduced intake
Fe deficiency anaemia
Faltering growth
