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
beta-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
beta-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
beta-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
beta-tryptase levels were observed in some patients who had neither elevated total
tryptase nor elevated
histamine levels. Unlike patients without detectable
beta-tryptase levels, patients who had detectable
beta-tryptase levels had a significant correlation between total
tryptase and
histamine levels (P <.05).
CONCLUSIONS: