<prompt> A 13-year old girl with Menorrhagia having Von Willebrands disease will show :Isolated prolonged PT with a normal PTTProlongation of both PT and PTTProlongation of thrombin timeIsolated prolonged PTT with a normal PT  <response>: Von Willebrands factor acts as a plasma carrier of factor VIII and circulates in the blood as factor VIII-VWF complex. Its deficiency therefore impairs the intrinsic pathway of coagulation and prolongs the GPTT as the intrinsic pathway of coagulation. Ref:Kligman, Behrman, Jenson, Stanton 2008, Chapter 477, VON WILLEBRAND DISEASE, In the book, Nelsons Textbook of Pediatrics, Volume 2, 18th Edition, New Delhi, Page 2073 