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Should all patients with acute undiagnosed angioedema have mast cell tryptase levels assessed?

Three Part Question

In [patients with acute undiagnosed angioedema] are [mast cell tryptase levels] better than [clinical impression] at [determining diagnosis]?

Clinical Scenario

A 21 year old ,ale with no family history of angioedema and no clear allergen exposure has an acute episode of urticaria, genital oedema and stridor which requires IV hydrocortisone and antihistamines in the Emergency Department. Would mast cell tryptase levels help to make a diagnosis?

Search Strategy

MEDLINE 1950 to 2010 June Week 5 and Embase 1980 to 2010 Week 27 using the OVID interface on the world wide web on 12/7/2010
CINAHL using the EBSCOhost on the world wide web on 12/7/2010
MEDLINE and Embase - (Hereditary Angioedema Type III/ OR Angioedema/ OR "Hereditary Angioedema Types I and II"/ OR AND (exp Tryptases/ OR
LIMIT to English Language and Humans
CINAHL - (Angioedema) AND (Tryptase)

Search Outcome

MEDLINE - 16 papers, 3 relevant
Embase - 66 papers, 3 relevant
CINAHL - 1 paper, 0 relevant
MEDLINE and Embase found the same 3 papers that were relevant

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Bruno et al
8 patients with chronic acquired urticaria-angioedema vs 7 healthy controlsCase-control studySerum tryptase levels(mean ± SD.: 9.6 ± 4.3 μg/l) vs (3.0 ± 1.2μg/l)Very small study size Chronic angioedema studied, not acute
Regner et al
1 patient with ACE-i induced angioedemaCase reportMast cell tryptase levelsAcute 9.78ng/mL (norm <11.5ng/mL) vs 4 days later ~2-4ng/mLNo actual value given for the base line 4 days later Case report only
1 patient with Angiotensin II blocker angioedemaCase reportMast cell tryptase levels20 mins (11.7μgL -1); 8hrs (15.1 μgL -1); 12hrs (13.1 μgL -1); 2mths (5.4 μgL -1); Normal (<13.5 μgL -1)Case report


Despite a very few case of documented tryptase levels in angioedema there seems to be situations in which patients have elevated levels of mast cell tryptase when suffering an acute episode of angioedema. There are also cases in which the level is not elevated clinically but is significantly elevated compared to the patients baseline. Thus the tryptase level during an acute episode may be beneficial in discovering the diagnosis.

Clinical Bottom Line

More trials need to be conducted to see in which types of angioedema tryptase levels are elevated. Until then taking the mast cell tryptase level during an acute attack of angioedema may be useful in determining a diagnosis at a later date compared to a patients base line tryptase level. The evidence suggests that taking tryptase levels during an acute attack at presentation, at approximately 8 hours and 12 hours after presentation and a baseline after resolution could help with a diagnosis.


  1. Bruno, G., Andreozzi, P., Magrini, L., Graf, U., Santangeio, G., Zaino, S. Mast cell activation in acquired chronic urticaria-angioedema The Science of the Total Enviroment 2001; 270:77-81
  2. Regner, K.R., Riegert-Johnson, D.L., Volcheck, G.W. Serial measurements of Serum Tryptase in Angioetensin Converting Enzyme Inhibitor-Assosciated Angioedema Mayo Clin Proc 2003; 78:655-656
  3. Nielsen, E.W. Hypotensive shock and angio-oedema from angiotensin II receptor blocker: a class effect in spite of tripled tryptase values Journal of Internal Medicine 2005; 258:385-387