D2.254 - Thyroid Autoantibody Seroconversion in Chronic Spontaneous Urticaria: Insights from Omalizumab Treated Patients

This study aimed to evaluate the clinical and laboratory characteristics associated with anti–TPO IgG seroconversion in patients with chronic spontaneous urticaria (CSU) receiving omalizumab therapy.

Fifty-four CSU patients who developed anti-TPO IgG seroconversion during follow-up were compared with age-, sex-, and baseline total IgE–matched CSU patients who remained anti-TPO–negative throughout follow-up. Demographic characteristics, disease duration, treatment course, routinely assessed laboratory parameters, and disease activity scores were retrospectively analyzed. Within the seroconversion group, patients were further categorized based on their disease control status during the period of anti-TPO positivity.

Patients with anti-TPO IgG seroconversion exhibited higher disease activity and required add-on treatment more frequently. Within the seroconversion group, patients experiencing disease flare-up showed higher rates of NSAID sensitivity, increased antihistamine requirement, more frequent eosinopenia, and significantly lower total IgE levels. Total IgE at the time of seroconversion was identified as the only independent predictor of disease control. Early seroconversion was associated with a greater need for additional therapy, whereas late seroconversion correlated with higher baseline total IgE levels.

Changes in anti-TPO IgG status during omalizumab treatment may be accompanied by disease flare-up, altered IgE dynamics, eosinopenia, and increased need for treatment escalation in a subset of CSU patients. The findings suggest a possible shift toward an autoimmune-dominant phenotype that may influence disease control, without implying a direct causal relationship between IgE-targeted therapy and disease progression. Monitoring of thyroid autoimmunity–related parameters may provide clinically relevant information for individualized management strategies in CSU.