Congenital Coagulopathies (Part II) Flashcards
Causes VWF activity to rise
Physical stress such as cold, exertion, or a child’s cry- ing or struggling during venipuncture
T/F: vWF activity rises when the phlebotomist allows the tourniquet to remain tied for more than 1 minute before venipuncture and descends if the specimen is stored in the refrigerator before testing.
TRUE
Concern over the poor reproducibility of results of the VWF:RCo assay has led to development of the
VWF collagen- binding (VWF:CB) assay.
Rheumatoid factor and heterophile antibodies interfere to cause
False positive
Specimen mishandling such as prolonged tourniquet application, plasma refrigeration, filtration, or ultracentrifugation lead to
False positives, false negatives, or false phenotypes such as misidentifying a type 1 as a type 2 VWD
Mild bleeding may resolve with the use of localized measures, such as
Limb elevation, pressure, and application of ice packs
PRICE is an athlete’s acronym for
for protection, rest, ice, compression, and elevation
May respond to estrogen and desmopressin acetate, which trigger the release of VWF from storage organelles
Moderate bleeding
is an antidiuretic hormone analog used to control incontinence in diabetes mellitus and bedwetting; release of VWF from storage organelles is a side effect
Desmopressin acetate
Is consistently effective for type 1 and subtype 2M VWD and generally useful for subtype 2A.
DDAVP, or oral spray form, Stimate
inhibit fibrinolysis and may help control bleeding when used alone or in conjunction with desmopressin acetate.
Lysine analogs e-aminocaproic acid and tranexamic acid
For treatment of severe VWD (type 3) and subtype 2B, three commercially prepared human plasma-derived high- purity preparations are available that provide a mixture of VWF and coagulation FVIII:
Humate-P, Alphanate, and Wilate.
Essential to determine whether the given amount produced the target level of VWF and to follow its degradation between doses
VWF:Ag assay
Is a recombinant VWF that provides no accompanying factor VIII.
Vonvendi
Are congenital single-factor deficiencies marked by anatomic soft tissue bleeding.
Hemophilias
Congenital deficiency of factor VIII is called
Classic hemophilia or hemophilia A.
Is two-chain, 285,000-Dalton protein translated from the X chromosome.
Factor VIII
When the coagulation cascade is activated, thrombin cleaves plasma FVIII and releases a large polypeptide called
B domain
Sometimes called the tenase complex, cleaves and activates coagulation factor X at a rate 10,000 times faster than free factor IXa can cleave factor X
VIIIA/IXa complex
Sometimes called the tenase complex, cleaves and activates coagulation factor X at a rate 10,000 times faster than free factor IXa can cleave factor X
VIIIA/IXa complex
T/F: VIII deteriorates in storage. Donor blood collected in standard citrate-dextrose-phosphate preservative provides 30 units/dL FVIII activity after 28 days’ storage or approximately 50 units/dL in leukodepleted donor blood.
TRUE
Are exquisitely painful and cause temporary immobilization.
Acute joint bleeds
Cause inflammation and eventual permanent loss of mobility, whereas bleeding into muscles may cause nerve compression injury, with first tempo- rary and then lasting disability
Chronic joint bleeds
T/F: The severity of hemophilia A symptoms is inversely proportional to FVIII activity.
TRUE
