Walk into the Clinical Blood Sciences lab at Croydon University Hospital and you can’t miss them: a pillar covered in laminated wall charts, each one a grid of red and green marker strokes climbing towards a 95% goal line. They track urgent turnaround times for tests like troponin, U&Es and CRP, day by day, month by month. They’re simple. They’re visible. And according to the team behind them, they’re changing how the lab works.
Specific IgE
| Category | Immunology and PRU |
|---|---|
| Turnaround time | Weekly |
Additional information
Interpretation of specific IgE results
Specific IgE results should be interpreted in the context of the clinical picture, including the history of any suspected reactions and the symptoms experienced by the patient, as well as any other investigations such as skin prick testing or challenge testing.
Positive results suggest a patient has been sensitised to a particular allergen, meaning that their immune system is capable of making IgE to that allergen, but this does not necessarily mean that the patient will have a symptomatic allergic reaction to that allergen.
The higher the specific IgE result, the more likely a patient is to have a reaction to that particular allergen, but this does not predict how mild or severe a reaction might be, and it is possible to have a high specific IgE concentration to an allergen but no symptomatic reactions.
Historically, allergy results were reported in Grades, derived from the radioallergosorbent test (RAST) method, but this is no longer in use and there is little value in trying to apply these Grade boundaries to specific IgE concentrations determined by modern immunoassay techniques.
More information about specific allergies can be found on the webpage for the Clinical Immunology service at St Helier Hospital.
To discuss specific cases, clinicians can contact the Clinical Immunology team at St Helier Hospital for adults or local paediatric team for children.
Methodology
The Immunology Laboratory and Protein Reference Unit analyses total and specific IgE using the Immulite immunoassay. Where the required allergen is not available on Immulite, testing is done on the Phadia immunoassay if possible. Results run on Phadia will have a statement added so that it is clear that it was run on Phadia instead of Immulite.
Both methods are calibrated against the same international reference preparation, but due to differences in allergen preparation, numerical results for specific IgE to the same allergen derived from the two methods are not interchangeable. Doctors are therefore advised to take care when comparing specific IgE results from our laboratory with results from a different laboratory, or with results determined before the Immulite method was introduced in our laboratory on 8 September 2025.
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