Anaphylaxis — DCE Clinical Case

Focused history — what you must establish

• Episode reconstruction, hour by hour: for each episode — everything eaten in the preceding six hours and exactly when, alcohol, exercise before or after eating, NSAIDs or other new medicines, intercurrent illness, insect exposure, menstruation, and the first symptom with its progression [1].
• Severity markers: which systems were involved, whether hypotension or collapse occurred, adrenaline doses required, and whether symptoms recurred after resolution — her second episode needing two doses marks her as a higher-risk phenotype [2].
• The running clue: the second episode during a run after an evening meal raises food-dependent exercise-induced anaphylaxis — ask specifically what she ate before running, and whether the same meal without exercise has ever caused symptoms [6].
• Cofactor and medication audit: regular and intermittent NSAIDs, any ACE inhibitor or beta-blocker, asthma or eczema history, and alcohol patterns — each amplifies reactions, and the cardiovascular drugs worsen outcomes [2].
• The safety-net gap: what she was actually discharged with, whether she can use the device, what she has been told, and what she now avoids — one device, no training and no plan is the commonest systems failure in this case [1].
• Her frame: food anxiety, fear around running, and what she most wants to be able to do safely.

Examination priorities

Skin for urticaria pigmentosa and a Darier sign (a wheal raised by stroking a pigmented lesion suggests cutaneous mastocytosis), dermatographism, and any residual angioedema; ENT examination for nasal polyps and upper-airway stigmata of atopy; chest for asthma control; cardiovascular examination and the medication reconciliation it prompts; and finally — ask her to produce her autoinjector and demonstrate it on a trainer [4] [1].

Presentation template (deliver this to the examiner)

“Ms Roberts is a 34-year-old runner with recurrent anaphylaxis — two episodes in eight months, one attributed to shellfish but never confirmed, and one exercise-associated episode requiring two adrenaline doses. The pattern raises food-dependent exercise-induced anaphylaxis, and her discharge after the second episode was incomplete: one device, no training, no plan, no referral. My priorities are to reconstruct both episodes, check a baseline tryptase, confirm or refute the shellfish attribution with properly timed testing, rebuild her safety net with two devices, training and an action plan, control her cofactors, and refer her to immunology — while addressing the anxiety that is already restricting her life.” [1] [6]

Management — what you will actually do

1. Investigate: baseline serum tryptase today (she is beyond 24 hours from any reaction); if persistently elevated, pursue clonal mast-cell disease with KIT D816V and haematology referral. Specific IgE and skin-prick testing to shellfish and the implicated meal components at least 4–6 weeks after her last reaction, interpreted strictly against the history [3] [4].
2. Rebuild the safety net today: prescribe two adrenaline autoinjectors, train her on a trainer device with teach-back, issue a written action plan (ASCIA), and arrange medical-alert documentation — the complete discharge bundle the emergency department missed [1].
3. Cofactor control: explicit advice about exercise within several hours of eating trigger-suspect meals, alcohol caution, and NSAID review; optimise asthma if present; review any ACE inhibitor or beta-blocker [2].
4. Refer: immunology for definitive trigger workup — including consideration of supervised challenge if testing and history diverge — and for management of confirmed food-dependent exercise-induced anaphylaxis; venom immunotherapy stands as the model of disease modification if any venom trigger emerges from the history [5].
5. Follow the trajectory: an episode diary with cofactor fields, review after testing, and escalation of prophylactic options if idiopathic episodes continue [4].

Probing questions

“The emergency department called the first episode shellfish anaphylaxis. Do you accept that?” — “Provisionally, not finally. The label was made in the acute setting without testing, and her second episode does not fit it. I will test specifically — timed beyond the false-negative window — because a wrong label both restricts her diet and closes the trigger hunt prematurely” [1].

“What is food-dependent exercise-induced anaphylaxis and why does it fit?” — “A reaction that occurs only when a specific food — classically wheat — is combined with a cofactor, most often exercise, within a few hours. Either element alone is tolerated. Her second episode, running after dinner with no reaction to the same foods at rest, is the textbook pattern, and the management is separating food from exercise by several hours plus the standard safety net” [6].

“Would you give her anything to take regularly?” — “While the workup proceeds, a daily non-sedating antihistamine is reasonable background cover, particularly if episodes prove idiopathic and frequent — understanding it does not treat or prevent anaphylaxis itself. There is no role for maintenance steroids. The definitive levers are trigger identification, cofactor control, and immunology-led prophylaxis if episodes recur” [4] [6].

“Her tryptase in the emergency department was normal. Is she in the clear?” — “No. A single acute tryptase — especially in food-associated reactions — is often normal, and without a baseline it cannot be read as a delta. Her baseline today is the informative test, and an elevated baseline would pivot the whole case toward mast-cell disease” [3] [4].