Summary

Introduction and objectives. Disorders of Gut-Brain Interaction (DGBIs), also known as functional gastrointestinal disorders (including functional dyspepsia and irritable bowel syndrome [IBS]), share overlapping symptoms with food allergies, such as diarrhoea, nausea, bloating, and abdominal pain. Nickel is the most common contact allergen, responsible for sensitising up to 20% of the general population, with possible systemic involvement (Systemic Nickel Allergy Syndrome, SNAS), often characterised by gastrointestinal (GI) symptoms. The aim of this study was to assess the prevalence of nickel allergy in paediatric and adult patients with GI symptoms consistent with DGBIs and to evaluate the diagnostic accuracy of the nickel atopy patch test (APT).

Materials and methods. This prospective observational study involved patients of both sexes (aged 4-65 years) with GI symptoms consistent with functional dyspepsia or IBS according to the Rome IV criteria. Upon enrolment, patients underwent medical history review, clinical and auxological assessments, and a nickel sulphate patch test (APT). Subsequently, all patients followed a nickel-free diet and, after 4 weeks, underwent an oral food challenge (OFC).

Results. Between January 2025 and January 2026, 200 patients (mean age 16 ± 5 years; 125 were female) with gastrointestinal symptoms consistent with DGBIs were consecutively assessed at two tertiary centres for allergic and gastrointestinal disorders. At the end of the diagnostic process, a definitive diagnosis of SNAS was established in 77 of the 200 patients. The nickel APT was positive in 90 subjects (45%). Seventy-five of the 90 patients with a positive nickel APT showed regression of GI symptoms on a nickel-free diet and recurrence of symptoms during the OFC. Two patients with negative APT results experienced resolution of GI symptoms on a nickel-free diet and recurrence during the OFC with nickel. The overall diagnostic accuracy of the nickel sulphate APT was as follows: PPV 83.3%, NPV 98.2%, sensitivity 97.4%, and specificity 87.8%.

Conclusions. Nickel allergy is common in subjects with GI symptoms consistent with functional dyspepsia or IBS. The APT has good diagnostic sensitivity in these patients and may be a useful screening test for identifying SNAS. The inclusion of an allergy work-up in patients with functional dyspepsia or IBS could open up new diagnostic and therapeutic possibilities.

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Authors

Laura Carucci - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Valeria Ciminera - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Erika Caldaria - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Raffaele Federico Iorio - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Paola D'Alessio - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Dario Marziali - Kantonsspital Graubuenden, Chur, Switzerland, Department of Internal Medicine, Kantonsspital Graubuenden, Chur, Switzerland

Antonio Masino - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Maria Sacco - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Giuseppe Falco - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Serena Coppola - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Alessandra Agizza - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

Roberto Berni Canani - Department of Translational Medical Science, University of Naples Federico II, Naples, Italy

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How to Cite
Carucci, L., Ciminera, V., Caldaria, E., Iorio, R. F. ., D’Alessio, P., Marziali, D., Masino, A., Sacco, M., Falco, G., Coppola, S., Agizza, A., & Berni Canani, R. (2026). Potential role of Nickel Allergy in Disorders of Gut-Brain Interaction. Italian Journal of Pediatric Allergy and Immunology, 67(2). https://doi.org/10.53151/2531-3916/2026-2531
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