Usefulness and Limitations of Sequential Serum Tryptase for the Diagnosis of Anaphylaxis in 102 Patients

Abstract

Background: The diagnosis of anaphylaxis is based on clinical history since no reliable biological marker is currently available to confirm the diagnosis. Objective: It was the aim of this study to determine sequential serum tryptase concentrations during anaphylaxis and to evaluate its potential as a diagnostic marker. Methods: We performed a prospective study including patients with acute anaphylaxis (according to the National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network criteria) attending the emergency department. Demographic characteristics, anaphylactic triggers, specific risk factors, clinical characteristics and management of anaphylaxis were recorded. Serum tryptase was measured at 1–2 h (T1), 4–6 h (T2) and 12–24 h (T3) following onset of the episode and at basal conditions (TB). Results: A total of 102 patients were included (63 females, mean age 47.4 ± 19.1 years). Tryptase concentration at T1 (19.3 ± 15.4 µg/l) was significantly higher than at T2, T3 and TB (all <11.4 µg/l; p < 0.0001). Importantly, tryptase was not raised in 36.3% of cases; furthermore, in 60.6% of these patients, no changes were observed in tryptase levels comparing T1 and TB (ΔT1–TB = 0). Tryptase was more frequently elevated in more severe anaphylaxis (p < 0.0001) and positively correlated with the grades of severity (p < 0.001, r = 0.49). Anaphylaxis was more severe and tryptase concentration higher when the causative agent was a drug compared to food, both at T1 (p = 0.045) and at TB (p = 0.019). Age and coronary risk factors were associated with more severe anaphylaxis (p = 0.001). Conclusion: Tryptase is a biomarker related to the severity of anaphylaxis. However, since its concentration remains unaltered in a considerable number of patients during acute anaphylaxis, there is a need for more reliable diagnostic biological tests.

World Allergy Organization Anaphylaxis Guidelines: 2013 Update of the Evidence Base

“…In a prospective study in adults, serum total tryptase concentrations were measured sequentially 1-2, 4-6, and 12-24 h after the onset of anaphylaxis symptoms and at baseline (follow-up). In 62% of the patients, initial tryptase levels were elevated (mean 19.3 ± 15.4 μg/l) with positive correlation between grades of severity and tryptase levels (p < 0.001, r = 0.49) [48]. …”

Serum Baseline Tryptase Level as a Marker for the Severity of Anaphylaxis

“…Baseline measurements are useful for allowing comparison to acute measurements, therefore enhancing diagnostic capacity. Although anaphylactic reactions to intravenous drugs have been shown to elicit greater increases in tryptase levels than oral triggers such as foods [13], our observational study has not identified significant differences in sBT levels and the types of triggers involved, but sBT levels were significantly higher among patients with more severe anaphylaxis. Our results are in keeping with those of Sahiner et al [23], who showed the relevance of sBT levels in predicting the risk of anaphylaxis in food allergy: a cutoff of 5.7 ng/mL was associated with a 50% probability of moderate-severe anaphylaxis.…”

“…The use of tryptase measurement for the diagnosis of anaphylaxis is well established [13, 15, 22]. However, one single acute measurement of the tryptase level may not be decisive to establish the correct diagnosis of anaphylaxis.…”

Anaphylaxis during general anaesthesia: experience from a drug allergy centre in theUK

“…Normal tryptase levels do not exclude the possibility of anaphylaxis, which can remain normal in 36% of patients who had clinically defined anaphylaxis. 31 A possible explanation is anaphylaxis attributed to local release of tryptase (e.g. in laryngeal oedema), which may not be sufficient to increase the total serum tryptase concentration; alternatively, there may be a greater participation of basophils than mast cells in the mechanism of anaphylaxis in some situations.…”