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Test Code LAB307 Von Willebrand Battery Agn + Factor VIII

Synonym

  • PTT (VW)
  • F8, RCF, VWFAG
  • vWF Antigen and Factor VIII
  • vWF Immunologic and Factor VIII
  • vWF Antigen and Factor 8
  • vWF Immunologic and Factor 8

Profile Information

Reporting Name Available Separately Always Reported
PTT Yes No
Factor VIII Yes No
Ristocetin Cofactor Yes Yes
VW Factor Ag Yes Yes

Specimen Required

Preferred Container/Tube: 3.2% Citrate Blue Top - 2.7 mL
Specimen Volume: 2.7 mL
Acceptable Container/Tube: 3.2% Citrate Blue Top - 1.8 mL
Specimen Volume: 1.8 mL
Platelet poor plasma (PPP):
Specimen Volume: 2 - 1 mL aliquots platelet poor plasma (PPP)
Specimen Minimum Volume: 1 - 1 mL aliquot platelet poor plasma (PPP)

Specimen Collection Information

For Outreach, other than OSU Patient Service Centers: Samples must be processed and received frozen/must remain frozen in transit. 

For sending frozen plasma specimens, process immediately upon receipt. Centrifuge capped specimen tube in accordance with CLSI H21, at a speed and time required to consistently produce platelet-poor plasma (PPP = platelet count <10 K/uL). Transfer PPP into plastic aliquot tubes, cap and freeze. DO NOT transport until specimens are completely frozen. 

Specimen Stability Information

Ambient: 
     Whole blood: 4 hours
      Platelet poor plasma: 4 hours
Frozen: 
      Platelet poor plasma: PPP removed from the cells and frozen at -20°C or ideally -70°C.

Rejected Due To

  • Ambient WB specimens >4 hours old
  • Ambient PPP specimens >4 hours old
  • Clotted specimens
  • Underfilled or overfilled tube
  • Hemolysis

Testing Algorithm

Samples will be sent out for von Willebrand Multimeric analysis (HEM5) when the RCF/VWAG ratio is <0.8. and either the RCF or VWFAG is <80%. Or if either (RCF/VWFAG) are <40%.

Reflex Tests

Reporting Name Available Separately Always Reported
Multimeric, Von Willebrand Yes No

Reference Values

PTT
24.0-34.3 sec

 

Factor VIII
0-4 days: 50-178 % Activity
5-29 days: 50-154 % Activity
30-89 days: 50-157 % Activity
90-179 days: 50-125 % Activity
180-365 days: 50-109 % Activity
1-5 years: 59-142 % Activity
6-10 years: 58-132 % Activity
11-16 years: 53-131 % Activity
17+ years: 50-200 % Activity

 

Ristocetin Cofactor
40-200 % Activity

 

VW Factor Ag
0-4 days: 50-287 %
5-29 days: 50-254 %
30-89 days: 50-246 %
90-179 days: 50-206 %
180-365 days: 50-197 %
1-5 years: 60-120 %
6-10 years: 44-144 %
11-16 years: 46-153 %
17+ years: 50-180 %

Cautions

VWF is an acute phase reactant. Elevated levels are seen during pregnancy, estrogen therapy, inflammation, acute infection, post surgery, physical exercise, or a stressful situation. Individuals with type O blood group have lower levels of vWF compared to other blood groups. In classical hemophilia, von Willebrand factor antigen levels are normal or increased, whereas in type I von Willebrand disease, the levels are very low or undetectable. Von Willebrand factor antigen levels may be normal in von Willebrand variants.

Method Description

PTT: Mechanical clot detection initiated by Calcium in the presence of cephalin (platelet substitute) and a particulate activator (silica).

VWF Ag: Immuno-turbidimetric method (STA - Liatest VWF:Ag)

Factor VIII: One Stage Clotting Assay

Ristocetin Cofactor: Ability of patient plasma to agglutinate formalin-fixed normal platelets in the presence of ristocetin.

Performing Lab

Clinical Lab UH

Day(s) Performed

Monday through Friday (excludes OSU holidays)

Report Available

Same day/1 day

Reporting Name

PTT (Part of Von Willebrand Workup)
Von Willebrand Workup - Special Coagulation

CPT Code Information

85730
85240
85246
85245

LOINC Code Information

14979-9
3209-4
6014-5
27816-8