Dermatology

Anesthesia

Anaphylaxis

Systemic mastocytosis

Angioedema

Immunology

Mathematics

Elevation (ballistics)

Internal medicine

Geometry

Mast cell

Nausea

Allergy

Tryptase

Medicine

Journal of Allergy and Clinical Immunology

To the Editor: Idiopathic anaphylaxis is a well described type of anaphylaxis for which no identifiable provocative agent exists.1Lenchner K. Grammer L.C. A current review of idiopathic anaphylaxis.Curr Opin Allergy Clin Immunol. 2003; 3: 305-311Crossref PubMed Scopus (35) Google Scholar Serum tryptase levels, a marker of mast cell activation, can be used in the diagnosis of anaphylaxis.2Schwartz L.B. Metcalfe D.D. Miller J.S. Earl H. Sullivan T. Tryptase levels as an indicator of mast-cell activation in systemic anaphylaxis and mastocytosis.N Engl J Med. 1987; 316: 1622-1626Crossref PubMed Scopus (668) Google Scholar Only 1 known case report exists of elevated tryptase levels in a patient who had a single episode of idiopathic anaphylaxis.3Tanus T. Mines D. Atkins P.C. Levinson A.I. Serum tryptase in idiopathic anaphylaxis: a case report and review of the literature.Ann Emerg Med. 1994; 24: 104-107Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar We describe the case of a patient with idiopathic anaphylaxis and an elevated mature tryptase level ∼26 hours after the onset of symptoms. The patient is a 54-year-old man who presented for office evaluation after having episodes of anaphylaxis for more than 10 years. Symptoms during his episodes included urticaria, pruritus, facial and extremity angioedema, nausea, vomiting, diarrhea, lightheadedness, syncope, and documented hypotension. The severity of his episodes was variable from mild symptoms of angioedema to more severe anaphylaxis with urticaria, angioedema, and hypotension necessitating emergency department admissions. The frequency of his episodes varied between 4 and 18 per year, with an apparent increase in frequency the year before his evaluation. History failed to reveal an inciting factor, including exercise, foods, medications, and insect stings. His past medical history was notable only for hypertension treated with amlodipine. His physical examination while asymptomatic was remarkable only for minimal nasal turbinate edema. Skin prick tests to a panel of 79 foods and spices were negative. Food dye and preservative challenges were also negative. Complete blood count with differential, general chemistries, C1 esterase inhibitor, and complement levels were normal. Based on his history and laboratory evaluation, a diagnosis of idiopathic anaphylaxis was made. The patient was initially instructed to have a serum tryptase level measured with his next episode. Two months later, approximately 3 hours after eating breakfast, he developed pruritus and urticaria, mild swelling of his hands and feet, and periorbital and lip edema, followed by throat tightness and severe gastrointestinal distress including nausea, vomiting, and diarrhea. He also experienced lightheadedness that was orthostatic in nature. He received no medical treatment for this episode and simply stayed at home. In the past, the patient had used self-injectable epinephrine, but he found the relief very short-lived and therefore stopped using it. During this episode, he began a 24-hour urine collection for methylimidazoleacetic acid. His methylimidazoleacetic acid was elevated at 10.1 mg/24 h (normal < 5). Previous baseline 24-hour urine collection for histamine was normal. The next day, his symptoms had resolved with the exception of a few urticarial lesions. Approximately 26 hours after the initial episode began, a serum tryptase level was measured at 110 ng/mL mature (β) tryptase (normal mature tryptase < 1 ng/mL). All symptoms with the exception of urticaria had resolved by the time this serum sample was obtained. Baseline serum obtained 6 months and 2 years later revealed mature tryptase levels of <1 ng/mL and total tryptase levels of 2 and 3 ng/mL, respectively (normal total tryptase, 1-15 ng/mL). All tryptase assays were performed at Virginia Commonwealth University. To our knowledge, this is just the second case report of an elevated serum tryptase level in a patient with idiopathic anaphylaxis. In the previous case report, no mention of baseline tryptase levels or follow-up was made.3Tanus T. Mines D. Atkins P.C. Levinson A.I. Serum tryptase in idiopathic anaphylaxis: a case report and review of the literature.Ann Emerg Med. 1994; 24: 104-107Abstract Full Text Full Text PDF PubMed Scopus (27) Google Scholar The fact that our patient had transient elevations of mature (β) tryptase and a urinary histamine metabolite with an acute episode and normal levels of both mature and total tryptase while asymptomatic strengthens the diagnosis of anaphylaxis involving mast cell activation and makes systemic mastocytosis unlikely. This patient has now been followed for 10 years, and although the frequency of his anaphylactic episodes has decreased substantially, no specific etiology has been determined. The mechanism of idiopathic anaphylaxis has yet to be elucidated, but it is important to make the diagnosis accurately early in the disease course, because the condition is known to recur.1Lenchner K. Grammer L.C. A current review of idiopathic anaphylaxis.Curr Opin Allergy Clin Immunol. 2003; 3: 305-311Crossref PubMed Scopus (35) Google Scholar Although further investigation is needed, serum tryptase levels obtained during or even after an episode of idiopathic anaphylaxis may aid in making the diagnosis correctly. Previously, it has been shown that the half-life of serum mature tryptase is about 2 hours, and it has been suggested that tryptase should be checked within 4 hours of an anaphylactic episode.4Schwartz L.B. Yunginger J.L. Miller J. Bokhari R. Dull D. Time course of appearance and disappearance of human mast cell tryptase in the circulation after anaphylaxis.J Clin Invest. 1989; 83: 1551-1555Crossref PubMed Scopus (403) Google Scholar This case is unique because the elevated tryptase level was drawn ∼26 hours after the onset of symptoms and approximately 12 hours after resolution of all symptoms with the exception of a few urticarial lesions. This suggests that in some individuals with anaphylaxis, a serum tryptase may be elevated well beyond this 4-hour interval. In some patients suspected of having anaphylaxis, serum samples may be available only more than 4 hours after the episode. In such cases, determination of periacute and baseline tryptase levels may indeed be useful in securing a diagnosis of anaphylaxis involving mast cells.5Schwartz L.B. Effector cells of anaphylaxis: mast cells and basophils.Novartis Found Symp. 2004; 257: 65-74Crossref PubMed Google Scholar

Prolonged elevation of serum tryptase in idiopathic anaphylaxis