0071643192.pdf

HEMATOLOGY, ONCOLOGY, ALLERGY,

AND IMMUNOLOGY

Bleeding disorder with normal

platelet count, PT, and PTT

suggests von Willebrand

disease.

■ FFP if bleeding predominates

■ Cryoprecipitate to replace fibrinogen

■ Platelet transfusion if <50,000/μL with active bleeding or if <10,000/μL

■ Vitamin K 10 mg parentally

■ Heparin if thrombosis fibrin deposition predominates or if purpura fulmi-

nans is present

Von Willebrand Disease

This is the most common hereditary bleeding disorder. The von Willebrand

factor facilitates adherence of platelets to injured blood vessels and also stabi-

lizes factor VIII in plasma.

There are three forms of vWF characterized by their quantitative or qualita-

tive defects:

■ Type I, the most common form, has a partial decrease in vWF.

■ Type II has dysfunctional vWF.

■ Type III has almost no vWF.

SYMPTOMS/EXAM

■ Epistaxis, gingival bleeding, menorrhagia, GI bleeding

DIAGNOSIS

■ aPTT may be normal or prolonged, normal platelet count, normal PT,

increased bleeding time

■ Abnormal assay of vWF activity, vWF antigen, or factor VIII coagulant (C)

activity

TREATMENT

■ Desmopression (DDAVP)

■ Stimulates release of vWF (and factor VIII) stored in vascular endothe-

lial cells

■ Indicted for type I disease

■ Factor VIII concentrates with vWF (Humate-P, Koate HS)

■ Primary therapy for types II and III disease

■ Should be used in all cases of serious bleeding

■ Cryoprecipitate

■ Contains vWF, but carries risk of infectious disease transmission, there-

fore is only recommended when factor VIII concentrate with vWF are

not available

A 25-year-old hemophiliac weighing 70 kg presents with a head injury

and decreased mental status after a high speed MVC. What is the level of

factor (in %) that is desired in this patient?

This patient must be presumed to have intracranial hemorrhage and re-

quires 100% factor replacement. Based on a starting factor level of 0% and with

each unit/kg of factor VIII raising the plasma level by 2%, the number of units of

factor required is 3500 (0.5 U/kg ×70 kg ×100% increase needed).