Factor VIII Assay

Test Code

FVIII

CPT Codes
85240

Preferred Specimen

1 Blue

Minimum Volume

Blue tops must be filled to Minimum Fill Indicator Line on tube.

Other Acceptable Specimens

none

Instructions

Outreach clients should double-spin the blue top plasma, remove the plasma from the RBC button, and freeze in a polypropylene tube.

Transport Container

Blue, polypropylene tube

Transport Temperature

Blue - RT Polypropylene tube - Frozen

Specimen Stability

Whole Blood - 4 hours RT Separated plasma - 4 hours at RT or 2 weeks frozen

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Sample must be free of clots and hemolysis.

Methodology
Clotting Time Measurement

Setup Schedule

Performed on Thursday; Dayshift

Report Available

Upon Completion of Analysis

Reference Range

Adult: 59 - 156 %

6 months: 50 - 109 %

3 months: 50 - 125 %

1 month: 50 - 157 %

5 days: 50 - 154%

1 day: 50 - 178 %

Clinical Significance

Coagulation factors are necessary for the normal function of the extrinsic and intrinsic coagulation systems. A deficiency of any of the factors will limit the function of the coagulation cascade. The systems used for measuring these coagulation factors are the Prothrombin Time (PT) and the Activated Partial Thromboplastin Time (APTT) which measure the factors of the extrinsic and intrinsic systems respectively. The substrate used to identify each deficiency is a commercially available plasma which is deficient in the specific factor to be assayed. The test is corrected proportionally to the amount of deficient factor in the unknown plasma. The percent activity in the unknown plasma can be determined from a standard curve prepared using dilutions of a known assayed commercial plasma. Prothrombin Time (PT) based assays will be used for factors of the extrinsic coagulation system (II, V, VII, X) and the Activated Partial Thromboplastin Time (APTT) for the intrinsic coagulation system (VIII, IX, XI, XII).

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.