The efficacy of Rituximab as an off-label treatment for pediatric multiple sclerosis (MS) has been well-documented, but dosing and dose modification has not been standardized. The effects of Rituximab on immunoglobulin (Ig) levels have been documented in adult MS patients, but not in pediatric MS patients.

In a retrospective chart review, we searched for pediatric MS patients who 1) used Rituximab as the sole disease modifying agent for MS 2) used Rituximab to only manage MS 3) had IgA, IgM and IgG measurements and 4) were <22 years old at dosing and Ig measurements.

Thirty-four patients had Ig measurements taken at least 40 days post Rituximab initiation. Rituximab dosing was 1000 mg per dose every 6.10 months on average. Of the 34 patients, 17 had Ig levels were within normal reference range after an average of 13.04 months of treatment. 17 patients had Ig levels below reference range after an average of 19.03 months of treatment. Patients with normal Ig values were on Rituximab therapy started on average at 16.35 years old, while patients with low Ig values started on average at 15.65 years old. All 17 had low IgM, 11 had only low IgM, 4 had low IgM and IgG, and 2 low IgM and IgA. 2 of 5 patients who received a lower dose (500 or 750 mg) following a low Ig measurement had subsequent Ig measurements, and neither returned to reference range Ig levels.

In pediatric MS patients treated with Rituximab, 50% had low Ig levels. Of the 2 patients treated with lowered Rituximab dosing for low Ig with follow-up Ig measurements, neither returned to reference range Ig levels.