Blood Testing
This test measures the amount of Specific IgE circulating in the blood that the immune system has produced against a suspected allergen.
The test is carried out on a small sample of blood, at your GP's surgery or at a hospital. It is usually taken from a vein in the arm, using a fine needle and a small syringe, causing minimal discomfort.
These tests are particularly useful when:
- The patient has a risk of an anaphylactic (shock) reaction, so skin prick testing would be considered unsuitable.
- When extensive eczema makes skin prick testing impractical.
- When antihistamine medication cannot be stopped because of the severity of the symptoms.
- Where unusual and rare allergens are suspected.
Results are available in around 7 to 14 days
and are reported in Classes of 0 - 6,
which indicate increasing sensitivity to an allergen.
Class 0 indicating a negative result,
Class 1 indicating a Sensitivity and
Class 6 indicating Extremely High Sensitivity.
A number of laboratories have now switched to recording specific IgE results different from the previous Grade or Class system shown above to reporting the actual level as shown on the right. This change has taken place to increase the accuracy and to potentially allow levels lower than Grade 1 to be reported. The increased accuracy may allow a change in specific IgE to be measured following a treatment or intervention. To the right is a guide to compare the new results alongside the Grade or Class system which are shown as numbered from 1 to 6.
| Class | IgE Levels KUA/L |
|---|---|
0 |
<0.35 |
1 |
0.35 - 0.69 |
2 |
0.7 - 3.4 |
3 |
3.5 - 17.4 |
4 |
17.5 - 49.9 |
5 |
50 - 99 |
6 |
>100 |
If you have difficulty obtaining the information you require please do not hesitate to contact our helpline on 01322 619898
