Asthma, rhinitis, other respiratory diseases
Histamine and tryptase levels in patients with acute allergic reactions: An emergency department–based study,☆☆

https://doi.org/10.1067/mai.2000.107600Get rights and content

Abstract

Background: Emergency department visits for acute allergic reactions are common. Although the diagnosis and classification of these allergic reactions is primarily empiric, it is not always clear whether certain signs and symptoms constitute systemic mediator release syndromes, such as anaphylaxis, and thus may warrant more aggressive therapy or follow-up. Objective: We sought to determine associations between various clinical signs and symptoms with both plasma histamine levels and serum tryptase levels in adult patients presenting to an emergency department with acute allergic syndromes. The clinical correlates of raised β-tryptase levels were also investigated. Methods: Ninety-seven adult emergency department patients were prospectively studied by using a questionnaire, physical examination, and serum-plasma sampling. Plasma histamine and serum total and β-tryptase levels were determined. Clinical groupings were compared for mediator levels by using simple and multivariate analysis. Results: Elevated levels of plasma histamine (>10 nmol/L) and serum total tryptase (>15 ng/mL) were observed in 42 and 20 patients, respectively. Detectable β-tryptase (≥1 ng/mL) was observed in 23 patients, including 15 of the patients with elevated total tryptase levels. Suspected food allergy incidences and the duration of reaction were similar in patients with increased histamine levels and in patients with increased tryptase levels. Increased total tryptase levels, histamine levels, or both were observed in some patients who did not have airway, cardiovascular, or abdominal signs. Histamine levels correlated better with clinical signs than tryptase levels. Histamine elevations (>10 nmol/L) were observed more frequently in patients characterized by the following clinical signs in univariate analysis: the presence of urticaria, more extensive erythema, abnormal abdominal findings, and wheezing. Total tryptase increases were observed more frequently only in patients with urticaria. Histamine levels correlated with initial heart rates. In multivariate analysis the extent of urticaria was the best single predictor of plasma histamine levels and of either an elevated histamine or tryptase level. Detectable β-tryptase levels were observed in some patients who had neither elevated total tryptase nor elevated histamine levels. Unlike patients without detectable β-tryptase levels, patients who had detectable β-tryptase levels had a significant correlation between total tryptase and histamine levels (P < .05). Conclusions: Raised histamine and, less commonly, raised tryptase levels are observed in almost 50% of patients presenting to emergency departments with acute allergic reactions. Some cases associated with systemic mediator release do not have classical features of severe anaphylaxis, such as hypotension or tachycardia. The lack of total tryptase elevations in many patients with elevated plasma histamine levels suggests basophil involvement. The clinical utility of β-tryptase determinations in the evaluation of acute allergic reactions needs further study. (J Allergy Clin Immunol 2000;106:65-71.)

Section snippets

METHODS

Patients from the Saint Vincents Hospital Emergency Department were recruited between May 1998 and April 1999 in a study approved by the institutional review board. Adult patients (>18 years old) were considered for recruitment if they demonstrated the following syndromes after an ingested food or ingested, inhaled, or injected drug or after contact with latex: acute urticaria, acute angioedema, acute unexplained stridor, or acute pruritic rash. The study targeted patients whose symptoms had

RESULTS

Among 98 patients recruited for the study, 91 received randomized antihistamine protocol treatment. On chart review, 9 patients had allergic manifestations for greater than 12 hours (two patients each at 15 hours and 48 hours and one each at 19, 40, 58, 69, and 120 hours). These patients were still included in the analyses. Tryptase determinations were performed on 96 patients. Plasma histamine determinations were performed on 89 patients. Improper specimen handling (hemolysis or delayed

DISCUSSION

Many of the patients described in this report would not be considered as having severe anaphylaxis.12 Hypotension was observed in only two patients. No patients had loss of consciousness or required cardiopulmonary resuscitation or intubation. Despite this relatively mild clinical picture, about half of the patients had elevations of either histamine or total tryptase, which is consistent with a diagnosis of anaphylaxis. More patients had histamine elevations than tryptase elevations. This

Acknowledgements

We thank the emergency department nursing staff and Kevin Kavookjian for their help in this study.

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    Supported in part by National Institutes of Health grant AI20487 (L. B. S.)

    ☆☆

    Reprint requests: Robert Y. Lin, MD, Saint Vincents Hospital, 153 W 11th St, New York, NY 10011.

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