Factor VIII Activity with Reflex to Bethesda Quantitative, Factor VIII
Ordering Recommendation
Order to diagnose factor VIII deficiency, detect factor VIII inhibitors, and monitor factor VIII replacement therapy.
Submit With Order
Mon, Wed, Fri
1-4 days
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Lt. blue (sodium citrate). Refer to Specimen Handling at aruplab.com for hemostasis/thrombosis specimen handling guidelines.  
Specimen Preparation
Transfer two 3 mL aliquots of platelet-poor plasma to ARUP Standard Transport Tubes. (Min: 2 mL/each)  
Storage/Transport Temperature
CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered.  
Unacceptable Conditions
Serum. Non-frozen and hemolyzed specimens.  
Ambient: 4 hours; Refrigerated: Unacceptable; Frozen at -20°C: 3 months; Frozen at -70°C: 6 months  
Reference Interval
Test Number Components Reference Interval
0030095Factor VIII, Activity 0-​6 years: 56-​191%
7-​9 years: 76-​199%
10-​11 years: 80-​209%
12-​13 years: 72-​198%
14-​15 years: 69-​237%
16-​17 years: 63-​221%
18 years and older: 56-​191%
Bethesda Quantitative, Factor VIII Effective May 19, 2014
0.5 BU or less
Interpretive Data
If Factor VIII activity is 20 percent or less, then Bethesda Quantitative, Factor VIII will be added. Additional charges apply.
CPT Code(s)
85240; if reflexed, add 85335
Component Test Code*Component Chart Name
0030028Bethesda Quantitative, F8
0030095Factor VIII, Activity
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Cross References
  • Bethesda Quantitative Factor VIII, Inhibitor
  • Coagulation Factor VIII Inhibitor Panel, Plasma
  • Factor 8 Inhibitor
  • Factor VIII Inhibitor Profile