Six-month changes in immunological biomarkers during levetiracetam monotherapy in children with epilepsy: a prospective observational cohort study

Levetiracetam (LEV) is widely used in pediatric epilepsy. However, prospective pediatric data on immunological changes during LEV treatment are limited and inconsistent. We measured immunological and hematological biomarkers before and after six months of LEV monotherapy in children with epilepsy. In this prospective observational cohort study, 52 children aged 2–15 years with newly diagnosed epilepsy were enrolled after starting LEV monotherapy by the treating clinician. Blood samples were collected before treatment and at six months to measure total IgG and its subclasses, IgA, IgM, CD4 + and CD8 + T-cell percentages, anti-tetanus IgG, and white blood cell count. Our paired analysis consists of thirty children with samples available at both time points. Immunoglobulin concentrations were also analyzed as age-adjusted Z-scores. Of the 52 enrolled children (42.3% female; mean age 7.39 ± 3.84 years), 30 completed the 6-month paired assessment. Baseline characteristics were similar between completers and non-completers. Mean total IgG decreased from 1048.1 ± 446.6 mg/dL to 864.9 ± 221.4 mg/dL (mean change − 183.3 mg/dL; 95% CI − 321.1 to − 45.4; P = 0.007). On age-adjusted analysis, total IgG decreased by 0.72 standard deviation (SD) ( P = 0.008), whereas IgG3 increased by 0.27 SD ( P = 0.010); both changes remained significant after false discovery rate correction (q = 0.031). The decline in IgG was more in children with higher baseline values, and the association persisted after correction for regression to the mean using Oldham’s method (ρ=−0.47, P = 0.009). At six months, 29 of 30 children had a total IgG within the age-specific reference range, and anti-tetanus seroprotection was maintained. An interaction test showed no sex-specific effects. All other markers did not change significantly. Six months of LEV monotherapy was associated with a statistically significant reduction in mean total IgG, while most other immunological markers were unchanged. Almost all children remained within the age-specific reference range, without clinically apparent immune dysfunction. While these findings provide valuable initial insights, further studies in larger, controlled cohorts with longer follow-up are needed to clarify long-term clinical implications. ISRCTN registry, ISRCTN16753384; retrospectively registered on 19 June 2026.