Allergic disorder

Question 1

What classification is used to describe underlying pathology of different hypersensitivity reactions

Answer 1

The Coombs and Gell classification

Question 1

What is meant by atopy

Answer 1

term used to describe a predisposition to having hypersensitivity reactions to allergens

Question 2

What are the different types of hypersensitivity reactions

Answer 2

Type 1- IgE antibodies to specific allergen trigger mast cell and basophils to release histamines and other cytokines
Acute reaction

Type 2- IgG and IgM antibodies react to an allergen and activate the complement system - haemolytic disease of newborn and transfusion reactions

Type 3- immune complexes accumulate and cause damage to local tissues. Eg SLE

Type 4- cell mediated hypersensitivity reactions caused by T lymphocytes - organ transplant rejection

Question 3

What are the 3 main ways to test for allergy

Answer 3

-skin pricking test
-RAST testing - involves blood tests for total and specific IgE
- food challenge test

Question 4

What do the skin prick test and RAST test assess

Answer 4

sensitisation and not allergy

makes these tests notoriously unreliable and misleading

Question 5

What is the most helpful in determining an allergic contact dermatitis

Answer 5

patch testing

Question 6

What is the gold standard investigation for diagnosing allergy

Answer 6

Food challenge testing - however requires lots of time and is only available in selected places

Question 7

How do you manage allergies

Answer 7

avoidance of allergen
prophylactic antihistamines
epipen for those at risk of anaphylactic shock

Question 8

What is treatment for allergic reactions following exposure of the allergen

Answer 8

Antihistamines- Cetirizine

Steroids - oral prednisolone, topical hydrocortisone or IV hydrocortisone

IM adrenaline in anaphylaxis