Other coagulation factor levels and vWF levels, antiphospholipid antibodies, autoimmune tests such as rheumatoid factor, ANA panels, and viral panels such as Epstein-Barr virus (EBV), cytomegalovirus (CMV), and hepatitis profiles should also be tested to rule out the other coagulation factor deficiencies or possible underlying causes. Here, VWF is linked to hepatitis A virus infection.