Allergies: Causes and Testing

The cause of allergy is a combination of someimportant factors: Familial (Genetic) predisposition, environmental incitation, and local protein allergens.

Features of allergy and tests available

Based on genetic inheritance, your family’s history of allergy or ‘Atopy’ is a major pointer. Families with fewer children favour allergic development. Males are prone to allergies than females. Prenatal maternal diet and smoking seem to contribute.Genes that are linked to allergy—genes carrying the ‘allergy predisposition’ have been identified on Chromosomes 5 and 11—the ‘atopy phenotype’. Obesity and Vitamin D deficiency can develop allergies.

Home environment activities in the first year of life are focal. Parental cigarette smoking may trigger an allergy. Infant diet, early introduction of allergenic foods may conflictingly prevent allergies. Allergic sensitisation may be promoted by air pollution; early use of day-care institutions, broad-spectrum antibiotics; and birth before the spring pollen season. Factors preventing allergies include certain viral illnesses and vaccines; living on a livestock farm; and intestinal microflora.This highlights the ‘hygiene hypothesis’, whereby children in modern cities are at higher risk of developing allergies.

Lastly, modest exposure to common aeroallergens and allergenic foods together with the above factors leads to early sensitisation.

Factors that reduce allergic sensitisationinclude but not limited to:

• Pet ownership (especially dogs & early exposure to farm animals)
• Living in close proximity with older siblings (germ swapping)
• Exclusive breastfeeding for the firstfour months

Factors that promote allergic sensitisation include but not limited to:

• Lack of older siblings (who carry germs that switch off allergies)
• No household pets
• Sterile Westernised homes

The Allergic March is simply the chronological and predictable progression of one clinical manifestation of allergy to the next. Allergies changes form from childhood to adulthood.

Specific Immunoglobulin E (IgE) is a marker for allergic sensitisation

This is the antibody in our blood and tissue that mediates allergy. It’s measured by blood on RAST tests and Skin Prick Tests. Specific allergies tend to be age-related.

Available reliable allergy tests

We can perform Skin Prick allergy tests for common inhalant and Food allergens or measure Total IgE in the blood. There’s also Phadiatop inhalant screen, Food Allergy screens, and over 450 individual RAST amongst other tests.

Skin Prick Allergy Testing and Methodology

This is one of the oldest and still the most sensitive allergy test available. It tests for specific IgE antibodies to inhalants. It’s performed using standardised glycerinated extracts of the various allergen extracts.

There are over 450 Immunocap RAST tests by Phadia(UK) for accurate allergy blood tests.

Total serum IgE in blood as an allergy indicator has been superseded by newer tests that are more specific.

The Phadiatop Inhalant allergy blood screen is used to diagnose respiratory allergy.

Allergy Tests for Food Allergy in Children are the fx5 food & fx1 nut allergy screen.

Pseudo-allergic or Anaphylactoid Reactions are not IgE mediated.

Confirming the allergen is important! It identifies the cause of allergic symptoms and institutes avoidance measures.