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HelpTest Code LAB3700 Factor 8 Assay
Clinical System Name
Factor 8 Assay
Synonyms
LAB3700
Factor 8
Factor VIII
Factor VIII Activity
Sample Requirements
Specimen: Whole Blood
Container(s): Lt. Blue/Citrate
Preferred Vol: (1) 2.7 mL
Minimum Vol: (1) 1.8 mL
Note: Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume. Use of a Vascular Access Device for the collection of coag testing is not recommended.
If this method is used it requires a 5 cc clearing volume; 3 cc for size 2 French catheter or smaller. Blood must be trasferred to the Lt Blue/Citrate tube by use of a blood transfer device to ensure proper fill.
Specimen should be centrifuged within one hour of collection.
Processing Instructions
Main Campus CPA: Core Technologist will process specimen. Deliver blood directly to Core Coag bench.
Reject due to: Clotted, Insufficient quantity (underfill), or Improper collection (overfill).
Spin: Y
Aliquot: Y
Storage location: Core 14 Freezer ( -70 C).
Core Technologist: Specimen should be centrifuged within one hour of collection. Transfer upper 3/4 layer of plasma to plastic tube affixed with large Epic aliquot label. Freeze one aliquot of plasma at -70 C. Preferred plasma volume: 1.0 mL, minimum plasma volume: 0.6 mL. Do not pool.
Off-site collection: Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volumel. Use of a Vascular Access Device for the collection of coag testing is not recommended. If this method is used it requires a 5 cc clearing volume; 3 cc for size 2 French catheter or smaller. Blood must be trasferred to the Lt Blue/Citrate tube by use of the blood transfer device.
Specimen should be centrifuged within one hour of collection. Transfer upper 3/4 layer of plasma to plastic tube affixed with large Epic aliquot label. Freeze one aliquot of plasma at -70 C. Preferred plasma volume: 1.0 mL, minimum plasma volume: 0.6 mL. Do not pool.
Non-Children's Hospital Off-site collection: Ship completely frozen on dry ice.
Children's Regional Clinics: Ship completely frozen in frozen Nalgene Labtop cooler with ice pack inside an insulated soft cooler.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Citrated platelet-poor plasma | Room temp | ≤4 h |
| Refrigerated | N | |
| Frozen -20 C or -70 C | ≤3 m |
Availability
| STAT | Performed | TAT |
|---|---|---|
| Y* |
Wednesday and Friday |
1-7 d |
*See ordering note above for STAT requests.
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Coagulation
Phone Number: 206 987-2617 (Client Services)
CPT Codes
85240
Methodology
Method: Electromagnetic mechanical clot detection system by STA-R MAX
Analytical Volume: 0.6 mL plasma
Limitations: Method is affected by improper collection, processing, and storage.
High hematocrit greater than or equal to 56% requires a citrate adjusted tube.
Emicizumab (Hemlibra) will affect all PTT-based assays and will overestimate the factor concentrations. Certain extended half-life formulation of recombinant factor VIII may give unreliable results with various factor VIII assays.
Reference Range
| % Activity | |
| Normal | 50 - 150 |
Critical Values
| % Activity | |
| Critical | < 30 |
Description
The quantitation of factor VIII in a patient's plasma can determine the presence and severity of factor VIII deficiency. It can be used to monitor treatment for hemophilia patients, and also used as part of the evaluation of Von Willebrands disease. Conversely elevated levels of Factor VIII is associated with mildly to moderately increased risk of venous thromboembolism.