Anaphylaxis, tryptase and MCAS - Twitter summary from #CSACI19 meeting
Anaphylaxis - Different Causes. Click here to enlarge the image.
Dr. Ellis @DrAnneEllis: Dr Moshe Ben Shoshan-care gaps in anaphylaxis.
The prevalence of anaphylaxis in the general population is at least 1.6%.
British guidelines recommend tryptase measurements in all cases of acute allergic reactions to confirm or refute the diagnosis of anaphylaxis.
Mary McHenry MD @maryjmchenry: Biomarkers for anaphylaxis include tryptase, histamine and 24hr urinary histamine - most useful is tryptase that can detect severe reactions if drawn within 60-90 min of reaction. No good evidence from high quality studies that steroids play a role in the treatment of anaphylaxis. Epinephrine is first line. Always!
Dr. Mariam Hanna, MD @PedsAllergyDoc: In UK: measure tryptase with children presenting with anaphylaxis or unknown picture acutely and repeat tryptase to get baseline level when well. Recent Canadian data suggests 87% of the time there will be an increase in tryptase from patients baseline. Canadian data: tryptase rarely drawn, less than 50% assessed by allergist, kids assessed more frequently than adults, 20% risk of recurrent reactions esp. in asthmatics or food allergy (except peanut - due to higher awareness), epinephrine underused!!
Dr. Ben-Shoshan: Factors why epinephrine is not used:
1) availability of epinephrine
2) poor symptom recognition
3) fear of using epinephrine (pain, side effects, etc.)
Dr. Ellis @DrAnneEllis: Suspected drug induced anaphylaxis had very low rates of referral to Allergists for confirmation / to refute the diagnosis.
The majority of anaphylaxis in mastocytosis is due to hymenoptera stings (wasps, hornets, yellow jackets etc).
Asthma is an important cofactor in anaphylaxis - 43 or 48 deaths due to anaphylaxis in the Pumphrey-study had evidence of pre-existing asthma and also weren't well controlled.
Wheat dependent exercise induced anaphylaxis is probably secondary to a "steal" phenomenon of blood supply where exercise leads to increased intestinal permeability and increased allergen absorption.
Asthma, insects, mastocytosis, age, male sex important predictors of increased risk of severe anaphylaxis.
Dr Mariana Castells - Idiopathic anaphylaxis - from mast cells to mastocytosis. Idiopathic anaphylaxis is at the center of mast cell disorders.
Every tissue has a different mast cell phenotype.
The alpha chain of fibrinogen is a preferred target of beta tryptase.
Many drugs can activate mast cell degradation through IgE independent mechanisms.
Mast cells that are spindle shaped and stain CD25 positive are not normal mast cells - prelude to mastocytosis. Andrew O'Keefe, MD @draokeefe: Dr Castells: Mast cell disorders can be very challenging to diagnose, even bone marrow biopsy can appear normal, unless you look for mast cells that stain CD25+. One measurement of serum tryptase is not enough. Significant increases from baseline may be seen though appear in the “normal” range, below 12. Dr Castells: every patient who has had anaphylaxis has PTSD. We in medicine underestimate the impact of anaphylaxis on patients.
Dr. Mariam Hanna, MD @PedsAllergyDoc: Dr. Castells shares an important clinical pearl: Tryptase is your friend. If in doubt, do a tryptase!
Dr. Ellis @DrAnneEllis: However, one third of the population does not have 2 copies of the tryptase gene and thus we lose that as a biomarker.
Strong advocacy to measure tryptase levels in all cases of anaphylaxis acutely.
Fuplications in TPSAB1 gene lead to increased levels of tryptase and symptoms similar to mast cell activation syndrome.
Many pathways/phenotypes of anaphylaxis recognized now. Type 1, cytokine release, complement mediated and mixed.
In MCAS - if a patient doesn't respond to antihistamines, cromolyn and montelukast combination therapy, its probably not actually MCAS.
Dr Castells - every person who have experienced anaphylaxis have a form of PTSD - fear is huge - unmet need in our practice.
Mast cell activation (MCA) and MCA syndrome (MCAS): They are not the same (click to enlarge the image).