Decreased platelet count in children with epilepsy treated with valproate and its relationship to the immature platelet fraction.

This study examined relationships between valproate (VPA) and platelet count and immature platelet fraction (IPF). We compared the platelet count and IPF among three groups of children: those treated with VPA, those treated with other antiepileptic drugs (AEDs), and a reference group. IPF was measured using flow cytometry, and absolute immature platelet count (A-IPC) was calculated. The platelet count was significantly lower in the VPA group than in other AED and reference groups. In all groups, IPF was negatively correlated with platelet count. IPF was significantly higher in the VPA group than in the reference group, whereas A-IPC was similar among all groups. After stratification of the platelet count, IPF and A-IPC of the three groups did not differ significantly in any strata. No relationship was observed between serum VPA level and platelet count, IPF, or A-IPC. Our study suggests that VPA is associated with a decreased platelet count, although thrombocytopoiesis is not affected, even in children with a reduced platelet count. The suppression of platelet production in the bone marrow is unlikely to be the cause of thrombocytopenia in patients treated with VPA.