What causes chronic urticaria in children? (etiology study)

This study examined some of the possible etiologies of chronic urticaria (CU) in children by focusing on causative factors such as:

- functional autoantibody to FcεRIα (via autologous serum skin test (ASST))
- IgE
- thyroid autoimmunity
- urticarial vasculitis
- parasitic infestation
- food allergy

Children 4–15 yr of age with chronic urticaria (CU) were investigated with:

- complete blood count
- erythrocyte sedimentation rate (ESR)
- antinuclear antibody (ANA)
- CH50
- free-T4 (FT4), thyroid stimulating hormone (TSH), anti-thyroglobulin and anti-microsomal antibody
- autologous serum skin test (ASST)
- skin prick tests (SPT) for foods
- food challenges
- stool examination for parasites

Patients with physical urticaria were excluded.

Eosinophilia and elevated ESR were found in 23% and 13%, respectively. High ANA titers were found in 2%.

None of these patients had clinical features of urticarial vasculitis, abnormal CH50 level, abnormal TSH and FT4. Anti-thyroglobulin and anti-microsomal antibodies were not detected.

Positive autologous serum skin test (ASST) was found in 38% (autoimmune urticaria). ASST is currently being replaced by anti-FceR1 autoantibodies.

Parasites
were found in 5% - without clinical correlation.

Skin prick tests (SPT) to foods was positive in 35%. Food avoidance was beneficial to the subgroup of patients with positive history of food allergy only.

This is my suggested laboratory workup for selected patients with chronic urticaria:


Diagnosis of Chronic Urticaria (click to enlarge the image).



Anti-FceR1 autoantibodies in chronic autoimmune urticaria: IgG against FceRI (receptor for IgE) (click to enlarge the image).

References:
Identification of the etiologies of chronic urticaria in children: A prospective study of 94 patients. Pediatric Allergy and Immunology, 2009.
Image source: Urticaria, Wikipedia, public domain.

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