Allergy testing Flashcards
What is is a allergy?
An allergy is a reaction your body has to a particular food or substance
The three different types of skin testing are:
Skin Prick Testing (SPT), Intradermal Testing (intracutaneous), Patch Testing
Why do we use skin prick testing?
•Used as a diagnostic tool to detect type 1 hypersensitivity reactions & identify sensitivity to:
-inhalants (e.g. pollen, dust mite, animal dander)
oFoods (e.g. peanut, dairy, gluten, egg)
oDrugs (e.g. penicillin)
oOccupational Allergens (e.g. latex)
oInsect Stings (e.g. wasp, bee)
Why is it important to take a clinical history?
It is vital for making a decision in making a diagnosis e.g. work environment, where they live etc.
What are some of the major indications for allergy testing?
RHINITIS, Asthma, suspected food or drug allergy, suspected insect sting
What is released in type 1 reaction? And as a result the effects are:
Vasoactive amines (histamine) , enzymes are released.
the effects are smooth muscle contraction and increased vascular permeability.
What are lipid mediators (leukotrienes and prostaglandins)?
they are activated as a result of mast-cell activation. They increase vascular permeability. Smooth muscle contraction. Stimulates muscle secretion. Chemo-attractants for T-cells, eosinophils, mast cells and basophils.
What are basophils?
Type of white blood cell (leucocytes)
•Only circulating leucocyte that contains histamine
•Protection from infectious disease/foreign invaders
•Like mast cells:
oActivated by antigen cross linking to undergo degranulation
Give 3 examples of allergy symptoms:
- Sneeze/Cough
- Bronchoconstriction/Wheeze•Running nose
- Rash (hives)
- Swelling
- Itchy eyes, nose, throat, mouth
- Anaphylaxis (Severe Allergic Reaction)
Give 5 examples of allergy symptoms:
- Sneeze/Cough
- Bronchoconstriction/Wheeze•Running nose
- Rash (hives)
- Swelling
- Itchy eyes, nose, throat, mouth
- Anaphylaxis (Severe Allergic Reaction)
What are some of the common allergen solution used in testing?
Trees-Birch, Weeds-Tree Mix Grasses-Rye, Meadow Cereals-Barley, Oat, Rye, Wheat Animals-cats, dogs Molds-Aspergillus, Cladosporium Indoor- House Dust Mite Foods-Wheat Flour, Milk, Egg, Shrimp, Lobster – Brazil, Peanut, Occupational-Latex
How long before the spt (skin prick test) is performed should antihistamine be discontinued?
Antihistamine therapy should be discontinued (e.g.48 hours)
What are the steps for performing SPT (skin prick testing)?
Clean if necessary (soap & water),
Skin should be marked with symbols/numbers for each allergen:
o Approximately 3 cm intervals (at least 2-3cm from the wrist)
•Appropriate allergen solutions are placed next to each symbol/number
•Skin is pricked immediately following application
Usually start with negative control and end with positive control (1% histamine)
Tip just enters superficial layer of skin (no blood drawn
Reactions to solutions are examined between 10 and 20 minutes
True or False, A reaction with a diameter of >3mm is negative?
False, Positive is a weal ≥ 3mm*
Histamine reaction should show a weal and flare reaction, True or False?
True,
