Blood test can be performed to determine substances that a child is allergic to. Unlike skin prick tests these tests are not interfered if the child is already taking an antihistamine medication. Results are best interpreted by an allergy specialist as not all positive test result relate with in-life allergy.
Immunoglobulin IgE is estimated in the blood and total and specific level to specific substances are ascertained. The result is then scored (or ‘graded’) 0 to 6, grade of 3 or more is significant of allergy.
|GRADE||IGE LEVEL (IU/L)||COMMENT|
|0||<0.35||Absent or undetectable IgE|
|1||0.35 – 0.69||Low level allergen specific IgE|
|2||0.70 – 3.49||Moderate level allergen specific IgE|
|3||3.50 – 17.49||Significant high level allergen specific IgE|
|4||17.50 – 49.99||Very high level allergen specific IgE|
|5||50 – 100.00||Ultra high level allergen specific IgE|
|6||>100||Extremely high level allergen specific IgE|
IgE Allergy blood tests can be undertaken on specific substances or can be part of an ‘allergy profile’ such as to inhaled substances, foods, nuts and seeds, fish, shellfish, cereals profiles and so on.
It is also possible to test for native and recombinant allergen components for further diagnostic predictions such as to cow’s milk, egg, fish, peanut, soybean, hazelnut components and many other allergens. ImmunoCAP ISAC enables measurement of IgE antibodies to a fixed panel of 112 components from 51 allergen sources in a single step.