Abstract
BACKGROUND: Factor X (FX) deficiency (FXD) significantly disrupts coagulation, potentially leading to severe bleeding. While inherited FXD is rare, with a prevalence of 1 in 500,000, acquired FXD is also uncommon and frequently linked to conditions such as light-chain amyloidosis. In rare cases, certain medications can cause FXD. KEY CLINICAL QUESTION: Here, we present a rare case of acquired FXD induced by valproic acid (VPA). This deficiency is associated with the presence of anti-FX antibodies. CLINICAL APPROACH: A 65-year-old man undergoing treatment for various conditions, including chronic kidney disease and type 2 diabetes, developed severe FXD (activity <2 U/L) following VPA administration for epilepsy. During FXD, the patient experienced significant bleeding episodes, necessitating FX replacement with prothrombin complex concentrate. Upon discontinuation of VPA, FX activity improved in 9 days, possibly suggesting a role of the drug in FXD. Interestingly, antibodies directed against FX have been identified. CONCLUSION: This case emphasizes the necessity for clinicians to be vigilant of hemostasis disorders associated with VPA, even though such occurrences are rare.