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HelpTest Code F_10 Coagulation Factor X Activity Assay, Plasma
Reporting Name
Coag Factor X Assay, PUseful For
Diagnosing deficiency of coagulation factor X, congenital or acquired
Evaluating hemostatic function in liver disease
Investigation of prolonged prothrombin time or activated partial thromboplastin time
Method Name
Optical Clot-Based
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Plasma Na CitOrdering Guidance
Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason, consider ordering a Coagulation Consultation.
Necessary Information
If priority specimen, mark request form, give reason, and request a call-back.
Specimen Required
Specimen Type: Platelet-poor plasma
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Light-blue top (3.2% sodium citrate)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.
2. Within 4 hours of collection, centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.
3. Aliquot plasma into separate plastic vial leaving 0.25 mL in the bottom of centrifuged vial.
4. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C, or, ideally at or below -40° C.
Additional Information:
1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.
2. Each coagulation assay requested should have its own vial.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Na Cit | Frozen | 14 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Special Instructions
Reference Values
Adults: 70-150%
Normal, full-term newborn infants or healthy premature infants may have decreased levels (≥15-20%), which may not reach adult levels for 180 or more days postnatal.*
*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing
Day(s) Performed
Monday through Friday
CPT Code Information
85260
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| F_10 | Coag Factor X Assay, P | 3218-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| F_10 | Coag Factor X Assay, P | 3218-5 |
Clinical Information
Factor X is a vitamin K-dependent serine protease that is synthesized in the liver. Its biological half-life is 24 to 48 hours. Factor X participates in both intrinsic and extrinsic pathways of coagulation (final common pathway) by serving as the enzyme (factor Xa) in the prothrombinase complex.
Congenital factor X deficiency is rare. Acquired deficiency is associated with liver disease, warfarin therapy, vitamin K deficiency, systemic amyloidosis, and inhibitors (rare). Deficiency may cause prolonged prothrombin time and activated partial thromboplastin time.
Interpretation
Acquired deficiency is more common than congenital deficiency.
Homozygous individuals: <25% activity
Heterozygous individuals: 25% to 50% activity
Cautions
Liver disease, warfarin therapy, or vitamin K deficiency may decrease factor X levels.
Method Description
The factor X assay is performed on the Instrumentation Laboratory ACL TOP using the prothrombin time (PT) method and a factor-deficient substrate. Patient plasma is combined and incubated with a factor X-deficient substrate (normal plasma depleted of factor X by immunoadsorption). After a specified incubation time, a PT reagent is added to trigger the coagulation process in the mixture. Then the time to clot formation is measured optically at a wavelength of 671 nm.(Owen CA Jr, Bowie EJW, Thompson JH Jr: Diagnosis of Bleeding Disorders. Second edition. Little, Brown and Company, Boston, MA. 1975; Cielsa B. Defects of plasma clotting factors. In: Hematology in Practice. 3rd ed. FA Davis; 2019:chap 17)