# Specific IgE to tropomyosin increases the diagnostic accuracy of shrimp allergy

## TL;DR

Measuring IgE to tropomyosin improves shrimp allergy diagnosis compared to traditional tests, but oral food challenges remain essential for confirmation.

## Contribution

This study demonstrates that tropomyosin-specific IgE testing offers higher specificity than skin prick tests or shrimp-specific IgE for diagnosing shrimp allergy.

## Key findings

- Tropomyosin sIgE had 91.9% specificity but only 23.1% sensitivity for diagnosing shrimp allergy.
- Combining SPT with tropomyosin sIgE increased specificity to 94.6%.
- Oral food challenge confirmed allergy in 26% of patients with suspected shrimp allergy.

## Abstract

Skin prick test (SPT) and the level of serum-specific IgE (sIgE) antibodies to shrimp have low specificity in the diagnosis of shrimp allergy. Measurement of sIgE to tropomyosin is available as a test, but the accuracy remains controversial. This study aims to evaluate the diagnostic accuracy of sIgE measurement to tropomyosin in the diagnosis of shrimp allergy and compare the diagnostic performance to SPT and sIgE to shrimp.

Patients with a history of immediate reaction to shrimp allergy were recruited. All participants underwent SPT with commercial shrimp extract. Measurements of sIgE to shrimp and tropomyosin were carried out. An oral food challenge (OFC) with shrimp was performed to confirm the diagnosis.

Fifty symptomatic patients (mean age 27.3 years) with suspected shrimp allergy were evaluated. OFC confirmed allergy in 13 (26%) patients. Diagnostic modalities offered distinct advantages and limitations. Tropomyosin sIgE (rPen a 1) yielded superior specificity (91.9%) at the cost of sensitivity (23.1%), while extract-based tests (SPT and shrimp sIgE) provided better sensitivity (46.2%–61.5%) but lacked specificity (43.2%–51.4%). Implementing a two-step algorithm—combining SPT with tropomyosin sIgE—successfully optimized specificity to 94.6%. Nevertheless, given the suboptimal predictive values across all methods (PPV 25%–50%; NPV 73%–77%), these tools alone cannot safely guide management, and OFC remains essential.

Measurements of sIgE to tropomyosin provided higher specificity and increased diagnostic efficiency than SPT and measurement of sIgE to shrimp for the diagnosis of shrimp allergy.