Allergy update 2013

Allergy – notes from a recent allergy update course with thanks to Dr Su Li, paediatric consultant @ Whipps Cross.

Useful websites:

www.allergyuk.org – good factsheets on rhinitis, oral allergy syndrome etc.

www.itchysneezywheezy.co.uk is a collaborative project for patients, their parents and health professionals on all aspects of atopic illness.

RCPCH allergy care pathways for health professionals (eczema, anaphylaxis, urticaria, mastocytosis, food, drug and venom allergies etc. etc.)

www.bsaci.org (stores patient management guidelines and has recently been accredited by NICE – milk, nut and penicillin allergy guidelines all currently in progress)

How to make a diagnosis:

1.  Allergy  focussed clinical history

2.  Allergy  tests – tests look at sensitisation not clinical allergy, defines probability of allergy

Skin prick tests

IgE tests

Provocation tests / food challenge

IgE ranges :

 

< 0.35 Grade 0
0.35 – 0.7 Grade 1
0.7 – 3.5 Grade 2
3.5 – 17.5 Grade 3
17.5 – 50 Grade 4
50 – 100 Grade 5
> 100 Grade 6

 

Test equivalence :

Skin prick < 3 mm 3-7 mm >7 mm
IgE < 0.35 0.35 – 50 > 50

 

Probability of allergy :

< 3 mm 3-7 mm > 7 mm
High clinical suspicion Possible allergy Probably allergy Allergic
50:50 Possible allergy Possible allergy Probably allergy
Low clinical suspicion Not allergic Possible allergy Possible allergy

 

If ‘possible allergy’ consider food challenge.

 

Peanut Allergy:

  • Your risk of anaphylaxis to peanut is 1% per year if you have a nut allergy.
  • If you have had anaphylactic reaction, your risk increases to 5% per year, therefore always prescribe Adrenaline Autoinjector (EpiPen).
  • The degree of positivity of a test does not change the risk of anaphylaxis.
  • Your risk of having a peanut allergy is 8 times more if you have a sibling with a nut allergy – consider screening siblings.

Eczema:

  • Common allergens associated with eczema are egg, peanut and cows milk.
  • If you are allergic to egg, consider testing for the peanut and milk as they often co-exist
  • Egg exclusion diets can improve eczema symptoms however there is an increased risk of anaphylaxis if you come into contact with egg whilst on an
    exclusion diet.
  • Consider a food challenge after 1 year as egg allergies often resolve.

Cows Milk Protein Intolerance:

  • This is a non IgE mediated disease, allergy testing will be negative.
  • Typical symptoms tend to be eczema or GI upset including reflux, vomiting, ‘colic’, constipation, loose stools, blood and mucous in stools.
  • Management includes a 2-4 week trial of extensively hydrolysed formula (Nutramigen / Peptijunior) or amino acid formula (Nutramigen AA / Neocate).
  • If breastfeeding, mothers need to go onto an exclusion diet (including soya).
  • Do not use over the counter partially hydrolysed formula milks, these still contain cows milk protein.
  • Refer to a dietician if on an exclusion diet.
  • Consider diagnosis of FPIES (food protein intolerance enteropathy syndrome).
  • Cows milk protein intolerance usually resolves around 14 months of age.
  • At this age, introduce soya milk first. If well tolerated, introduce cows milk.

 

 

Leave a Reply

Your email address will not be published. Required fields are marked *