Lupus anticoagulant induced by the combination of valproate and lamotrigine

A 5-year-old boy with generalized absence seizures was treated with valproa te (VPA), 30 mg/kg/day. One month after VPA introduction, routine examinati on showed moderate reduction in fibrinogen and prolonged partial thrombopla stin time (PTT). The search for lupus anticoagulant (LAC) was negative. Aft er 10 months of VPA treatment, seizures persisted, and lamotrigine (LTG), 2 mg/kg/day, was progressively given with VPA. Seizures disappeared, but PTT was more prolonged than before LTG introduction. The search for LAC was po sitive, and enzyme-linked immunosorbent assays (ELISAs) for immunoglobulin G (IgG) anticardiolipid antibodies were positive. Serum autoantibody screen and rheumatoid factor were negative; serum complement was normal. LAC even tually disappeared with VPA discontinuation. We believe that LTG may have e xacerbated an initially mild immune response induced by VPA without clinica l evidence of systemic disease. We therefore suggest that careful surveilla nce for LAC and systemic disease should be instituted when VPA is used with LTG.