ARUP's Laboratory Test Directory

0030026: Factor VIII Activity with Reflex to Bethesda Quantitative, Factor VIII

Test Mnemonic: F8 BETHR
Methodology: Clotting

Performed: Mon, Wed, Fri
(On call 24 hours for emergencies. If Factor VIII is greater than 20%, no further testing will be performed. If Factor VIII Activity is 20% or less, Bethesda Quantitative, Factor VIII will be performed.)

Reported: 1-4 days

Specimen Required:  
Collect: Five 5 mL lt. blue (sodium citrate). (Min: Four 5 mL) Refer to the Hemostasis/Thrombosis Specimens section in the front of this User's Guide for specimen collection instructions.

Transport: Two 4 mL aliquots of platelet-poor plasma, frozen. (Min: 5 mL) Submit specimens in two ARUP Standard Transport Tubes.

Pediatric Collection/Transport: 5 mL platelet-poor plasma, frozen.

Remarks: CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered. For hemophiliacs: note dose, date, and time of last factor VIII concentrate infusion.

Unacceptable Conditions: Serum.  Nonfrozen and hemolyzed specimens.

Stability: Ambient: 4 hours; Refrigerated: 4 hours; Frozen: 2 weeks

Reference Interval:
 
Test Number Components Reference Interval
0030095Factor VIII, Activity 0-6 years: 56-190%
7-9 years: 78-199%
10-11 years: 83-226%
12-13 years: 74-205%
14-15 years: 69-241%
16-17 years: 63-225%
18 years and older: 56-190%
 Bethesda Quantitative, Factor VIII No inhibitor detected.

Note:
If Factor VIII activity is 20% or less, then Bethesda Quantitative, Factor VIII will be added.

CPT Code(s):
85240 Factor VIII; if reflexed, add 85335 Bethesda Quantitative