High plasma antithrombin levels in acute hepatitis A.

Background: Laboratory testing of antithrombin serves to demonstrate a decreased concentration that is indicative of a thrombotic tendency. We report unexpected high levels of antithrombin in a patient with hepatitis A. Methods: A 37-year-old woman with a 4-week history of acute hepatitis A was studied. The diagnosis of cholestatic hepatitis A was confirmed by positive serology and liver biopsy. The patient recovered completely within 6 months. Results: Antithrombin activity was increased (234%; reference range, 80-120%). This high activity was confirmed by an antithrombin antigen of 210%. On recovery antithrombin activity returned to normal. Conclusions: We are unaware of other reports of such high levels of antithrombin, in particular in patients with hepatitis A. It is not clear whether the high concentration observed in this case is due to an acute-phase reaction or to impaired clearance by the liver. The presence of a molecular variant with different secretion characteristics is unlikely, since antit...