Rare but well recognized allergic condition, about half related to a food trigger.
Anaphylaxis can occur with any degree of exercise, does not need to be extreme, but typically follows submaximal exercise pretty quickly. Deaths are fortunately rare.
- Exercise induced increase in gastric permeability
- increased tissue transglutaminase activity in gut
- Exercise induced blood flow redistribution
- Mast cell heterogeneity
- Basophil trigger by increased plasma osmolality
- Mast cell trigger by acidosis
All sound plausible but little evidence!
Co-factors play a role in many cases eg alcohol (but unpredictable), NSAIDs (85% will have reduced threshold, and severity increases too), infection, heat/cold – some evidence too for menstruation, anti-acids, stress, sleep deprivation (as in anaphylaxis). Co-factors also multiply risk of reaction.
Mostly wheat, including hidden sources eg soap, shampoo, cream.
SPT useful, also IgE omega-5-gliadin. But gold standard is provocation test (and still only 70% sensitive). No uniform protocol – use same as for exercise induced bronchoconstriction? Do 1 hour after meal with suspected trigger.
Prescribe adrenaline auto-injector. Avoid exercise 4-6 hours after food intake. Discuss unplanned exercise!