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Test Code FVIII Factor 8 Assay, LAB306


Activated Partial Thromboplastin Clot Based Assay

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements


Preferred:Full blue-top (sodium citrate) 1.8mL tube-Hemolyzed or short draw specimen is not acceptable.

Specimen Volume:  0.5mL sodium citrate plasma
Stability: centrifuged specimens at 2-4°C or at 18-24°C must be tested within 4 hours from the time of specimen collection. 

Collection Instructions: Forward promptly. If there is a delay in transport of >4 hours or if mailing time exceeds 4 hours, spin down, remove plasma from cells and freeze immediately in plastic vial. Send specimen frozen. Specimen stability is ≤2 weeks when frozen at -20° C.

NOTE: Patients with a hematocrit of >55% must be recollected using an altered amount of sodium citrate

Reference Values

50 - 150% activity

Day(s) Test Set Up

Monday through Friday (days only)

Test Classification and CPT Coding


Useful For

Hemophilia A is a sex-linked hemorrhagic disease caused by reduced circulating Factor VIII.  In patients with the disease, the degree of Factor VIII deficiency dictates the severity of the bleeding disorder.  Approximately 10-40% of normal Factor VIII activity is required for minimal hemostasis; below this range a tendency toward bleeding is apparent.

Report Available

1 day upon receipt