Chromogenic Factor X

Label Mnemonic:	CH10
Epic code:	LAB1020
Order form:	Laboratory Requisition
Supply order:	Supply Order Form
Billing:	Billing Policies
CPT code:	85260

Specimen(s):

Plasma More information

Collection Medium:

Light Blue top tube 2.7 mL (Na Citrate)

Minimum:

Full draw; 2.7 mL light blue top

Rejection Criteria:

Short drawn tube, clot, traumatic tap (excessive hemolysis).

Testing Schedule:

0800-1630 Monday, Wednesday and Friday. If you need results STAT, call Hematology resident (0800-1630, M-F) at 356-8628. All other times page the Pathology resident on-call at 3404.

Turn Around Time:

24-36 hours

Reference Range:

59 – 130%

Therapeutic reference range is 20 – 40%

Interpretive Data:

An approximate Chromogenic Factor X range of 20-40% corresponds to a therapeutic INR range of 2.0-3.0. This assay can be used for monitoring warfarin therapy in patients with lupus anticoagulants. Anti-phospholipid antibodies may influence the prothrombin time and resulting INR calculation, causing it to not accurately reflect the true level of anticoagulation.

Rosborough, T.K. and Shepherd, M.F. Unreliability of International Normalized Ratio for Monitoring Warfarin Therapy in Patients with Lupus Anticoagulant. Pharmacotherapy 2004;24(7):838-842.

McGlasson, D.L., Romick, B.G., and Rubal, B.J. Comparison of a Chromogenic Factor X Assay with International Normalized Ratio for Monitoring Oral Anticoagulation Therapy. Blood Coagulation and Fibrinolysis 2008;19:513-517.

Test Limitations:

This test is to be used for coumadin monitoring of patients with positive Lupus anticoagulants.

Methodology:

Activity detection by chromogenic substrate

Sample Processing:

Double-centrifuge specimen to prepare platelet-free plasma.
Immediately centrifuge specimen at 3500 RPM for 12 minutes.
Using a plastic transfer pipette, carefully remove plasma from cells avoiding the platelet/buffy coat.
Place plasma into a labeled plastic tube.
Centrifuge plasma again at 3500 RPM for 12 minutes.
Remove the top of the plasma and place into a labeled plastic tube.
Freeze double-spun plasma within 4 hours of collection time at -20 degrees C or below.

Sample Storage:

Freeze specimen immediately.

Transport Instructions:

Place labeled specimen into zip-lock type biohazard bag; seal bag.
Place requisition into outside pocket of bag.
Place dry ice on top of specimen in Styrofoam container.
Samples received thawed will be cancelled.

See Additional Information:
Phlebotomy Tubes and Order of Draw
Hemolysis Chart
Impact of Common Anticoagulants on Coagulation Tests