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Test Code Factor 8 Factor 8 Assay  

Clinical System Name

Factor 8 Assay
 

Synonyms

Factor 8

Factor VIII
Factor VIII Activity

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.

Sample Requirements

Specimen: Whole Blood

Container(s): Lt Blue/Citrate

Preferred Vol: (2) 1.8 mL tubes or (1) 2.7 mL tube

Minimum Required Vol: 1.8 mL tube

 

Note:  Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume, note fill line. Use of a Vascular Access Device for the collection of coag testing is not recommended.

If this method is used it requires a 5 mL waste volume; 3 mL for size 2 French catheter or smaller. Blood must be transferred to the Lt Blue/Citrate tube by use of a blood transfer device to ensure proper fill. 

Specimen should be centrifuged within 1 hour of collection.

Processing Instructions

Reject due to: Clotted, Hemolyzed, Insufficient quantity (under fill) or Overfill, and Improper collection.

Spin:N

Aliquot:N

Storage location: Core 14 Freezer ( -70 C).

 

Note: Deliver blood to Core Coag bench. Coag Technologist will process. Specimen should be centrifuged within 1 hour of collection. Spin whole blood, remove plasma. Transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label. Make two aliquots. Run the PTT and record result on the extra label. Freeze 2 aliquots in the -70 freezer coag rack.

 

 

 

Off-site collection: Preferred method of collection is venipuncture with vacuum fill. Test results are affected by incorrect blood volume, note fill line on tube. Use of a Vascular Access Device for the collection of coag testing is not recommended. If this method is used it requires a 5 mL waste volume; 3 mL for size 2 French catheter or smaller. Blood must be transferred to the Lt Blue/Citrate tube by use of the blood transfer device.

Specimen should be centrifuged within 1 hour of collection. Double spin, transfer upper 3/4 layer of plasma to plastic tube affixed with large computer label. Freeze at least one aliquot of 1 mL plasma (prefer TWO aliquots of 0.6 mL plasma) in plastic tubes at -70 C.

Ship frozen on dry ice.

.

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

 

* Call Coagulation laboratory for STAT testing.

Performing Laboratory

Seattle Children's Laboratory    

 

Department

Department:  Coagulation

Phone Number: 206 987-2617 (Client Services)

 

 

 

Reference Range

  % Activity
Normal 50 - 150

 

 

Methodology

Method:  Electromagnetic mechanical clot detection system by STA® - Compact Analyzer

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.

CPT Codes

85240

Critical Values

 

  % Activity
Critical < 30