Factor X Activity - Clot Based
| Factor X Activity - Clot Based | | | |
| Number | | 086306 |
| CPT | | 85260 |
| Related Information | | Factor Xa, Chromogenic Hemostasis and Thrombosis Appendix |
| Synonyms | | Stuart Factor ; Stuart Prower Factor |
| Special Instructions | | If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions. |
| Specimen | | Plasma, frozen |
| Volume | | 2 mL |
| Minimum Volume | | 1 mL |
| Container | | Blue-top (sodium citrate) tube |
Collection | | Blood should be collected in a blue-top tube containing
3.2% buffered sodium citrate.1 Evacuated
collection tubes must be filled to completion to ensure a
proper blood to anticoagulant ratio.2,3 The
sample should be mixed immediately by gentle inversion at
least six times to ensure adequate mixing of the
anticoagulant with the blood. A discard tube is not
required prior to collection of coagulation
samples.4,5 When noncitrate tubes are collected
for other tests, collect sterile and nonadditive (red top)
tubes prior to citrate (blue top) tubes. Any tube
containing an alternate anticoagulant should be collected
after the blue-top tube. Gel-barrier tubes and serum tubes
with clot initiators should also be collected after the
citrate tubes. Centrifuge and carefully remove the plasma
using a plastic transfer pipette, being careful not to
disturb the cells. Transfer the plasma into a LabCorp PP
transpak frozen purple tube with screw cap (LabCorp
No 49482). Freeze immediately and maintain
frozen until tested. To avoid delays in turnaround time
when requesting multiple tests on frozen samples, please
submit separate frozen specimens for each test requested.
Please print and use the Specimen
Collection Bulletin as a tube-filling guide. |
| Storage Instructions | | Freeze |
| Patient Preparation | | Avoid warfarin (Coumadin®) therapy for 2 weeks and heparin therapy for 2 days prior to the test. Do not draw from an arm with a heparin lock or heparinized catheter. |
| Causes for Rejection | | Gross hemolysis; clotted specimen; frozen specimen thawed in transit; improper labeling |
| Reference Interval | | Adults: 65% to 140%. In newborns, levels are lower but levels gradually reach adult ranges by 6 months of age.6 |
| Use | | Document factor X deficiency7,8,9 |
| Methodology | | Factor X activity is determined utilizing an aPTT-based one-stage clotting time assay. Factor X-depleted plasma is used as the substrate, and the clotting time with the patient plasma is compared to the clotting time of normal pooled plasma. |
| Additional Information | | Factor X is a 54.8 kilodalton vitamin K-dependent glycoprotein coagulation factor that is produced by the liver.7 Normal factor X's plasma concentration is approximately 10 mg/mL and half-life is about 40 hours.7 Factor X activation occurs by both the extrinsic and intrinsic pathways. Factor X deficiency should be considered when a patient with bleeding history has both extended protime (PT) and activated partial thromboplastin time (aPTT). The dilute Russell viper venom (dRVVT) measures the activation of factor X and will be prolonged in patients with deficiency.8,9 Congenital factor X deficiency is rare and is inherited as an autosomal recessive trait.7 This condition affects both males and females and the prevalence of hemophilia A is equal in all ethnic groups.7 A few cases of combined congenital factor II, VII, IX, and X factor deficiencies have been reported.7 Acquired deficiencies occur with significant hepatic dysfunction, with oral anticoagulant (coumarin) therapy, and in individuals with vitamin K deficiency.7,8 Factor X deficiency may be associated with primary systemic amyloidosis.7,9 Isolated factor X deficiency may also occur in patients with respiratory infections, acute myeloid leukemia, and with other malignancies.8 Acquired specific factor X inhibitors are rare in patients without congenital deficiency.7,8 Symptoms (homozygotes) include hematoma formation, postsurgical hemorrhage, menorrhagia, hematuria, and umbilical cord hemorrhage.7,8 Factor X plasma activity <30% may result in excessive bleeding following a traumatic event.7 Spontaneous bleeding similar to that observed in severe hemophilia may occur when the activity is <1%.7,8 |
| Footnotes | | - Adcock DM, Kressin DC, and Marlar RA, “Effect of 3.2% vs 3.8% Sodium Citrate Concentration on Routine Coagulation Testing,” Am J Clin Pathol, 1997, 107(1):105-10.
- Reneke J, Etzell J, Leslie S, et al, “Prolonged Prothrombin Time and Activated Partial Thromboplastin Time Due to Underfilled Specimen Tubes With 109 mmol/L (3.2%) Citrate Anticoagulant,” Am J Clin Pathol, 1998, 109(6):754-7.
- “National Committee for Clinical Laboratory Standardization: Collection, Transport, and Processing of Blood Specimens for Coagulation Testing and General Performance of Coagulation Assays; Approved Guideline,” Third Edition, Villanova: NCCLS Document H21-A3:11(23), 1999.
- Gottfried EL and Adachi MM, “Prothrombin Time and Activated Partial Thromboplastin Time Can Be Performed on the First Tube,” Am J Clin Pathol, 1997, 107(6):681-3.
- McGlasson DL, More L, Best HA, et al, “Drawing Specimens for Coagulation Testing: Is a Second Tube Necessary?” Clin Lab Sci, 1999, 12(3):137-9.
- Van Cott EM and Laposata M, “Coagulation,” Laboratory Test Handbook With Key Word Index, Jacobs DS, DeMott WR, and Oxley DK eds, Hudson, OH: Lexi-Comp, 2001, 327-58.
- Adcock DM, Jensen R, Johns CS, et al, Coagulation Handbook, Esoterix Coagulation, 2002.
- Roberts HR and Escobar MA, “Less Common Congenital Disorders of Hemostasis,” Consultative Hemostasis and Thrombosis, Kitchens CS, Alving BM, and Kessler CM, eds, Philadelphia, PA: WB Saunders Co, 2002, 57-71.
- Triplett DA, “Coagulation Abnormalities,” Clinical Laboratory Medicine, McClatchey KD, ed, 2nd ed, Philadelphia, PA: Lippincott Williams and Wilkins, 2002, 1033-49
|
|