von Willebrand factor multimeric levels and patterns in patients with severe preeclampsia.

The clinical manifestations of severe preeclampsia and thrombotic thrombocytopenic purpura are similar. Patients with thrombotic thrombocytopenic purpura have been demonstrated to have larger than usual von Willebrand factor multimers. Serial serum samples were taken from patients with severe preeclampsia, all with platelet counts less than 50,000. Von Willebrand factor multimeric patterns were normal in all the patients except one, who later proved to have chronic relapsing thrombotic thrombocytopenic purpura. All patients had elevated levels of von Willebrand factor. Although the clinical presentations of thrombotic thrombocytopenic purpura and severe preeclampsia with thrombocytopenia have many similarities, the underlying pathophysiology of each disorder appears to be different.