Von Willebrand disease laboratory findings: Difference between revisions
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==Laboratory Findings== | ==Laboratory Findings== | ||
Other tests performed in any patient with bleeding problems are | |||
The diagnosis of von Willebrand’s disease (VWD) begins with a relevant personal or family history of mucocutaneous bleeding. | |||
When VWD is suspected, the first level of testing comprises measurements of the the following: | |||
<ref name="pmid25673639">{{cite journal |vauthors=Sanders YV, Groeneveld D, Meijer K, Fijnvandraat K, Cnossen MH, van der Bom JG, Coppens M, de Meris J, Laros-van Gorkom BA, Mauser-Bunschoten EP, Leebeek FW, Eikenboom J |title=von Willebrand factor propeptide and the phenotypic classification of von Willebrand disease |journal=Blood |volume=125 |issue=19 |pages=3006–13 |year=2015 |pmid=25673639 |doi=10.1182/blood-2014-09-603241 |url=}}</ref> | |||
*VWF antigen (VWF:Ag) level, | |||
*VWF–ristocetin cofactor activity [VWF:RCo] as a measure of platelet-binding activity of VWF, and | |||
**The VWF:RCo assay may be replaced by newer assays that measure the binding of VWF to a recombinant wild-type GPIb fragment with the use of ristocetin or the spontaneous binding of VWF to a gain-of-function recombinant mutant GPIb fragment. | |||
*Factor VIII activity (FVIII:C). | |||
When the results of all first-level tests are normal, VWD is ruled out; because of biologic variability, however, the tests should be repeated if values are at the low end of the normal range or if VWD is strongly suspected. | |||
<ref name="pmid25673639">{{cite journal |vauthors=Sanders YV, Groeneveld D, Meijer K, Fijnvandraat K, Cnossen MH, van der Bom JG, Coppens M, de Meris J, Laros-van Gorkom BA, Mauser-Bunschoten EP, Leebeek FW, Eikenboom J |title=von Willebrand factor propeptide and the phenotypic classification of von Willebrand disease |journal=Blood |volume=125 |issue=19 |pages=3006–13 |year=2015 |pmid=25673639 |doi=10.1182/blood-2014-09-603241 |url=}}</ref> | |||
If these first-level tests reveal definitive abnormalities, a diagnosis of VWD can be made; if the results are not conclusive, second-level tests are required. VWD can be subtyped on the basis of these second-level tests. A rare platelet defect due to a gain-of-function mutation in the GPIbα receptor, known as platelet-type VWD, has a phenotype similar to that of type 2B VWD; the two disorders can be distinguished with the use of genetic testing. RIPA denotes ristocetin-induced platelet aggregation, VWF:FVIIIB VWF–FVIII binding activity, and VWFpp VWF propeptide. Persons with a bleeding tendency who have VWF levels between 30 and 50 IU per deciliter (the lower limit of the normal range) are classified as having “low VWF” or “possible type 1 disease” but are not classified as having definitive VWD. | |||
<ref name="pmid25673639">{{cite journal |vauthors=Sanders YV, Groeneveld D, Meijer K, Fijnvandraat K, Cnossen MH, van der Bom JG, Coppens M, de Meris J, Laros-van Gorkom BA, Mauser-Bunschoten EP, Leebeek FW, Eikenboom J |title=von Willebrand factor propeptide and the phenotypic classification of von Willebrand disease |journal=Blood |volume=125 |issue=19 |pages=3006–13 |year=2015 |pmid=25673639 |doi=10.1182/blood-2014-09-603241 |url=}}</ref> | |||
A platelet aggregation assay will show an abnormal response to ristocetin with normal responses to the other agonists used. A [[PFA-100|platelet function assay]] (PFA) will give an abnormal collagen/[[adrenaline]] closure time and in most cases (but not all) a normal collagen/[[adenosine diphosphate|ADP]] time. Type 2N can only be diagnosed by performing a "factor VIII binding" assay. Detection of vWD is complicated by vWF being an [[acute phase reactant]] with levels rising in [[infection]], [[pregnancy]] and [[stress (medicine)|stress]]. | |||
Other tests performed in any patient with bleeding problems are: | |||
*[[complete blood count]] (especially [[platelet]] counts), | |||
*[[APTT]] (activated partial thromboplastin time), | |||
*[[prothrombin time]], | |||
*[[thrombin]] time | |||
*[[fibrinogen]] level. | |||
*Testing for [[factor IX]] may also be performed if [[hemophilia B]] is suspected. | |||
Other [[coagulation factor]] assays may be performed depending on the results of a coagulation screen. | |||
*Patients with Von Willebrand disease will typically display a normal prothrombin time and a variable prolongation of partial thromboplastin time. | |||
==References== | ==References== | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Laboratory Findings
The diagnosis of von Willebrand’s disease (VWD) begins with a relevant personal or family history of mucocutaneous bleeding. When VWD is suspected, the first level of testing comprises measurements of the the following: [1]
- VWF antigen (VWF:Ag) level,
- VWF–ristocetin cofactor activity [VWF:RCo] as a measure of platelet-binding activity of VWF, and
- The VWF:RCo assay may be replaced by newer assays that measure the binding of VWF to a recombinant wild-type GPIb fragment with the use of ristocetin or the spontaneous binding of VWF to a gain-of-function recombinant mutant GPIb fragment.
- Factor VIII activity (FVIII:C).
When the results of all first-level tests are normal, VWD is ruled out; because of biologic variability, however, the tests should be repeated if values are at the low end of the normal range or if VWD is strongly suspected. [1] If these first-level tests reveal definitive abnormalities, a diagnosis of VWD can be made; if the results are not conclusive, second-level tests are required. VWD can be subtyped on the basis of these second-level tests. A rare platelet defect due to a gain-of-function mutation in the GPIbα receptor, known as platelet-type VWD, has a phenotype similar to that of type 2B VWD; the two disorders can be distinguished with the use of genetic testing. RIPA denotes ristocetin-induced platelet aggregation, VWF:FVIIIB VWF–FVIII binding activity, and VWFpp VWF propeptide. Persons with a bleeding tendency who have VWF levels between 30 and 50 IU per deciliter (the lower limit of the normal range) are classified as having “low VWF” or “possible type 1 disease” but are not classified as having definitive VWD. [1]
A platelet aggregation assay will show an abnormal response to ristocetin with normal responses to the other agonists used. A platelet function assay (PFA) will give an abnormal collagen/adrenaline closure time and in most cases (but not all) a normal collagen/ADP time. Type 2N can only be diagnosed by performing a "factor VIII binding" assay. Detection of vWD is complicated by vWF being an acute phase reactant with levels rising in infection, pregnancy and stress.
Other tests performed in any patient with bleeding problems are:
- complete blood count (especially platelet counts),
- APTT (activated partial thromboplastin time),
- prothrombin time,
- thrombin time
- fibrinogen level.
- Testing for factor IX may also be performed if hemophilia B is suspected.
Other coagulation factor assays may be performed depending on the results of a coagulation screen.
- Patients with Von Willebrand disease will typically display a normal prothrombin time and a variable prolongation of partial thromboplastin time.
References
- ↑ 1.0 1.1 1.2 Sanders YV, Groeneveld D, Meijer K, Fijnvandraat K, Cnossen MH, van der Bom JG, Coppens M, de Meris J, Laros-van Gorkom BA, Mauser-Bunschoten EP, Leebeek FW, Eikenboom J (2015). "von Willebrand factor propeptide and the phenotypic classification of von Willebrand disease". Blood. 125 (19): 3006–13. doi:10.1182/blood-2014-09-603241. PMID 25673639.