VON WILLEBRAND DISEASE (VWD) LABORATORY INVESTIGATION

VON WILLEBRAND DISEASE

1. VON WILLEBRAND DISEASE (VWD) NORSYAHIDAH BINTI SAZALI JTMP U29 RED CELL & HEMOSTASIS UNIT (RCH)

2. INTRODUCTION OF VWD

3. Von Willebrand disease is an inherited bleeding disorder that slows or prevents the blood’s ability to clot. This can cause abnormal, heavier bleeding after an injury. Typically, the blood clots normally after a cut or injury when the cells within the blood called platelets, gather together to plug a hole in the blood vessel to stop the bleeding. Patients with VWD, however, have low levels of a protein called von Willebrand factor that helps hold clots together when the body has normal levels of it. Some people with VWD may actually have normal levels of the protein, but it still fails to work properly to control blood clotting. The von Willebrand factor also carries another clotting protein, called factor VIII, which is involved in blood clotting. Factor VIII typically is either absent or not working properly in patients with hemophilia. VWD is the most frequently diagnosed bleeding disorder and it usually causes milder symptoms than hemophilia.

4. Most people with VWD have inherited it from a parent Autosomal dominant inheritance Autosomal recessive inheritance

5. SYMPTOMS OF VWD

6. Nosebleeds that last longer than 10 minutes ( Frequently ). Bleeding from cuts or injuries that lasts longer than 10 minutes. Bruising easily. Low in iron or have been treated for anemia. Heavy bleeding after any surgery including dental surgery. Have someone in your family who has been diagnosed with a bleeding disorder such as VWD or hemophilia.

7. For women, girls and those who menstruate:- Heavy periods, also called heavy menstrual bleeding (having to change one pad or tampon every hour) or periods that last longer than 7 days. Heavy bleeding after childbirth or miscarriage.

8. TYPES OF VWD

9. Type 1 : Quantitative abnormality of VWF . People with type 1 VWD have a low levels of VWF in their blood. Levels of VWF in the blood range from 20%-50% of normal. The symptoms are usually mild. Ricof/Ag ratio = > 0.6

10. Type 2 : Qualitative abnormality of VWF . People with type 2 VWD have a normal levels of VWF, but the factor doesn’t function as it should. Type 2 is broken down into four subtypes: 2A, 2B, 2M and 2N, depending on the specific way the VWF is defective. Symptoms are mild to moderate. Ricof/Ag ratio = < 0.6

11. Type 2A : Platelets are unable to stick to the wound site due to lack of high molecular weight VWF multimers. Type 2B : Amount of high molecular weight VWF multimers is insufficient due to an abnormal enchancement of its binding to platelets. Type 2M : Amount of high molecular weight VWF multimers is normal but it has impaired function. Type 2N : The VWF is incapable of binding with coagulation Factor VIII.

12. Type 3: Quantitative abnormality of VWF People with type 3 VWD have a very low levels or no VWF in their blood. Some people with this type of VWD may also be low in Factor VIII . Symptoms are typically severe, and include spontaneous bleeding episodes, often into their joints and muscles.

13. Acquired Von Willebrand Syndrome (VWS) A fourth type is Acquired VWS. This type of VWS in adults results after a diagnosis of an autoimmune disease, such as lupus, or from heart disease or some types of cancer. It can also occur after taking certain medications. This type is not hereditary.

14. LAB INVESTIGATION

15. Coagulation Profile & Factor VIII Level Prothrombin Time (PT) : Normal Activated Partial T hromboplastin Time (APTT) : Slightly prolonged / Prolonged Coagulation Factor VIII Level : Low / Normal

16. VWF:Ag & VWF:Rco To determine the amount and function of VWF, the level of antigen (VWF:Ag) and VWF activity with ristocetin cofactor (VWF:RCo) are measured. And if :- Amount of VWF is low : VWF:Ag - Low VWF:RCo - L ow VWF not functioning with Sufficient quantity of VWF : VWF:RCo - L ow Normal range:- VWF:Ag (52.9% - 182.5%) VWF:Rco (59.8% - 131.5%)

17. Thus,the results for VWF:Ag and VWF:RCo will be different,depending on the type of VWD. Special tests like multimer analysis and Collagen Binding A ssay (CBA) become necessary for confirmin g the type. Multimer analysis - to differentiate between subtype 2A and 2B CBA - to differentiate between subtype 2M and 2N

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