Immunoglobulin and serum protein electrophoresis requesting is changing on 8 July 2026. Clinicians can now request immunoglobulins only or immunoglobulins and electrophoresis. This change will enable doctors to more effectively request the tests that are clinically indicated and streamline laboratory testing, delivering improved turnaround times for these tests. This change will apply to Epsom & St Helier Hospitals and their associated GPs initially, and will then be rolled out to all service users in south west London.
Tryptase
| Category | Immunology and PRU |
|---|---|
| Turnaround time | Weekly |
Additional information
Potential anaphylactic reactions; three samples required:
1) At the time of the reaction
2) 1-2h after onset of symptoms (no later than 4h)
3) Baseline at 24h or follow-up allergy clinic appointment
Reference range: 2 – 14ug/L
Guidance for interpreting serum tryptase results (non-post-mortem samples)
Please note, this guidance does not apply to postmortem samples.
Raised serum tryptase:
Serum tryptase may be elevated acutely in systemic mast cell activation (IgE or non-IgE-mediated systemic reactions).
Samples should be taken immediately, 1-4 hours maximum after onset of symptoms and then at / after 24 hours, to establish a baseline.
Note that serum tryptase may increase significantly from resting concentration but remain within the reference range. This dynamic rise calculation is made using the formula: baseline tryptase x 1.2 + 2 ug/L. An acute rise in tryptase to more than this the resting concentration is suggestive of systemic mast cell activation.
However, note that systemic allergic reactions may occur with no significant increase in tryptase concentration, especially with reactions to foods and in children.
The serum tryptase concentration can be inappropriately lower if a sample is taken during fluid resuscitation, due to haemodilution.
Serum tryptase may be elevated persistently in Hereditary Alpha Tryptasaemia, renal impairment and haematological neoplasia (Clonal Mast Cell Disorders ie systemic mastocytosis, Primary Hyper-Eosinophilia and Myeloproliferative Diseases). In neoplastic disease the serum tryptase concentration may be monitored serially.
Low serum tryptase:
Serum tryptase concentrations below the reference range are not of any clinical significance.
Please note, the term resting or baseline tryptase refers to a patient’s serum tryptase concentration in their usual state of health. This is generally established from a sample taken at least 24h after any suspected reaction.
To discuss a specific case, call the Immunology Consultants on 020 8725 5106.
Resources:
National Audit on Intra-operative Anaphylaxis
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