Hemophilia and VWD
	Diagnosing VWD
	Recommended Tests
	Contact abp
	(ristocetin sulfate)

When asked about bleeding disorders hemophilia in most cases will be the first word to come to mind. Unfortunately, in many cases it is the only bleeding disorder we recognize, and sometimes patients with other bleeding disorders -- i.e. VWD -- are misdiagnosed and consequently receive the wrong therapy.

Hemophilia and VWD - Different Diagnosis

People with mild hemophilia and hemophilia carriers may have factor levels in the range expected for VWD, but will have normal levels of VWF antigen (VWF Ag) and Ristocetin Cofactor Activity, an activity measure of VWF. People with VWD show variable reductions in factor VIII, VWF Ag and Ristocetin Cofactor Activity. It is therefore important that VWF Ag and Cofactor assays are performed whenever a low factor VIII is found to differentiate between hemophilia A and VWD.

A usual coagulation screen will probably include:

 Platelet Count
 Bleeding Time
 PTT

For VWD patients, is this sufficient?

In VWD, the platelet count would be normal, and as already discussed; the bleeding time and PTT could also be normal due to external factors such as stress or exercise temporarily elevating the factor VIII levels.

It is important to remember that the diagnosis of VWD includes:

 Clinical History
 Drug History
 Physical Examination
 Family History
 Laboratory Investigation

In June 1996, the International Society on Thrombosis and Hemostasis (ISTH) Scientific Standardisation Committee arrived at a draft "Consensus Criteria for the Diagnosis of VWD Type 1". An excerpt from their report is shown below:

Recommended Laboratory Tests In Suspected VWD:

Screening Tests: complete blood count with differential and platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT), VWF:RCo. VWF:Ag

Screening or Confirmatory Tests: factor VIII level. ABO blood type

Confirmatory Tests: RIPA, VWF multimers

Criteria for laboratory tests:

Laboratory test results are comparible with VWD type I if the levels of both VWF:RCo and VWF:Ag are <2 SD below the population mean and ABO blood type adjusted mean on >2 determinations. If the tests are performed, RIPA must not indicate abnormal sensitivity on low concentrations of (ristocetin sulfate), and the plasma VWF multimer distribution must be normal.