Laboratory Medicine
Test Directory / Specific IgE
Specific IgE
Brown clotted serum, gel barrier or lithium heparin
| Test | Specific IgE |
|---|---|
| Common Abbreviations | SPE, RAST, SIgE |
| Profile | NA |
| Tube type | Brown clotted serum, gel barrier or lithium heparin |
| Clinical Indication | Allergen-specific IgE testing is performed to screen for an allergy (type I hypersensitivity) to a specific substance or substances in response to acute or chronic allergy-like symptoms in the patient. Many allergies are mediated by immunoglobulins of the IgE class acting as points of contact between the allergen and specialized cells. The IgE molecules bind to the surface of mast cells and basophilic granulocytes. Subsequent binding of allergens to cell bound IgE causes these cells to release histamines and other vasoactive substances, thereby initiating the events which are recognised as an allergic reaction |
| Specimen Type | Blood |
| Sample type | Serum or plasma |
| Minimum Volume | 1ml for every 5 allergens requested. |
| Special Precautions | No special requirements |
| Stability | 7 days at 2-8°C and 6 months at -20°C |
| Turnaround Time | 7 days |
| Laboratory | The majority of sIgEs are analysed at York Hospital See https://www.yorkhospitals.nhs.uk/our-services/a-z-of-services/lab-med/general-information/information-for-health-care-professionals1/advice-for-requesters-clinical-biochemistry/ download the document on ALLERGY TESTING. sIgEs not tested at York are sent to the Protein Reference Unit in Sheffield for analysis. |
| Reference Interval | Class 0:<0.10-0.35 KUA/L, Class 1:0.35-0.70 KUA/L, Class 2:0.70-3.50 KUA/L, Class 3:3.50-17.5 KUA/L, Class 4:17.5-50 KUA/L, Class 5:50-100 KUA/L, Class 6:>100 KUA/L |
| Limitations | The level of IgE present does not correlate to the severity of an allergic reaction, and where allergy has been outgrown a positive specific IgE may still be present. It is possible to have a positive specific IgE result to an antigen that is not a cause of allergy in the patient. It is essential that the results are interpreted alongside a full allergic history and any other tests that have been performed, such as skin prick tests. |
| Notes |
