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Query: UMLS:C0042109 (urticaria)
 6,569 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insect sting anaphylaxis and mast cell disorders are intertwined in a specific and unusual way. There may be specific subsets of clonal mast cell disorders that are predisposed to sting anaphylaxis. The clinical characteristics of the sting reactions should raise suspicion of underlying mastocytosis (eg, hypotension without hives especially in a male). A baseline serum tryptase level is helpful in the evaluation of patients with insect sting anaphylaxis because it correlates with important risks for these patients, and they have a high frequency of abnormally elevated baseline levels. Elevated baseline serum tryptase level has been reported to correlate with clonal mast cell disease in patients with insect sting anaphylaxis but may also indicate one of several possible underlying syndromes, including mast cell activation syndrome (MCAS), familial hypertryptasemia, and idiopathic anaphylaxis. There is some overlap in these conditions, so it is important to evaluate the clinical pattern at presentation as well as laboratory markers, and to consider bone marrow biopsy to make a final and specific diagnosis of clonal mast cell disease. The presence of venom-IgE does not prove that the patient's previous sting reactions were IgE-mediated, but even low levels of venom-IgE in patients with mastocytosis predispose to severe sting anaphylaxis. Evaluation of all these possible factors will affect the recommendation for venom immunotherapy.
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PMID:Insect Sting Anaphylaxis-Or Mastocytosis-Or Something Else? 3096 37

Hymenoptera venom allergy ranks among the top three causes of anaphylaxis worldwide, and approximately one-quarter of sting-induced reactions are classified as severe. Fatal sting reactions are exceedingly rare, but certain factors may entail a considerably higher risk. Delayed administration of epinephrine and upright posture are situational risk factors which may determine an unfavorable outcome of the acute anaphylactic episode and should be addressed during individual patient education. Systemic mastocytosis and senior age are major, unmodifiable long-term risk factors and thus reinforce the indication for venom immunotherapy. Vespid venom allergy and male sex likewise augment the risk of severe or even fatal reactions. Further studies are required to assess the impact of specific cardiovascular comorbidities. Available data regarding potential effects of beta-blockers and/or ACE inhibitors in coexisting venom allergy are inconclusive and do not justify recommendations to discontinue guideline-directed antihypertensive treatment. The absence of urticaria/angioedema during sting-induced anaphylaxis is indicative of a severe reaction, serum tryptase elevation, and mast cell clonality. Determination of basal serum tryptase levels is an established diagnostic tool for risk assessment in Hymenoptera venom-allergic patients. Measurement of platelet-activating factor acetylhydrolase activity represents a complementary approach but is not available for routine diagnostic use.
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PMID:Risk factors and indicators of severe systemic insect sting reactions. 3119 89

Anaphylaxis is a life-threatening systemic reaction, normally occurring within one to two hours of exposure to an allergen. The incidence of anaphylaxis in the United States is 2.1 per 1,000 person-years. Most anaphylactic reactions occur outside the hospital setting. Urticaria, difficulty breathing, and mucosal swelling are the most common symptoms of anaphylaxis. The most common triggers are medications, stinging insect venoms, and foods; however, unidentified triggers occur in up to one-fifth of cases. Coexisting asthma, mast cell disorders, older age, underlying cardiovascular disease, peanut and tree nut allergy, and drug-induced reactions are associated with severe or fatal anaphylactic reactions. Clinicians can obtain serum tryptase levels, reflecting mast cell degranulation, when the clinical diagnosis of anaphylaxis is not clear. Acute management of anaphylaxis involves removal of the trigger; early administration of intramuscular epinephrine; supportive care for the patient's airway, breathing, and circulation; and a period of observation for potential biphasic reactions. Only after epinephrine administration should adjunct medications be considered; these include histamine H1 and H2 antagonists, corticosteroids, beta2 agonists, and glucagon. Patients should be monitored for a biphasic reaction (i.e., recurrence of anaphylaxis without reexposure to the allergen) for four to 12 hours, depending on risk factors for severe anaphylaxis. Following an anaphylactic reaction, management should focus on developing an emergency action plan, referral to an allergist, and patient education on avoidance of triggers and appropriate use of an epinephrine auto-injector.
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PMID:Anaphylaxis: Recognition and Management. 3293 Dec 10


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