Fondaparinux Lvl (FON)
Department: Coagulation
Test Synonym(s): LAB3446, FON, Arixtra Assay, Anti-Xa Assay, Fondaparinux Level
CPT Codes: 85520
Methodology: Chromogenic
Reference Range: Therapeutic range: Typical range for a 7.5mg dose: 0.50 - 1.50 ug/ml
Specimen: Citrated platelet poor plasma - Requires double centrifugation if sending a plasma aliquot. Aliquot(s) must be frozen if not received by lab within 4 hours of collection.
Alternate Specimen: None
Pediatric Requirements: Pediatric: One 2.7mL Light blue top - 3.2% Sodium Citrate. Neonatal: One 1.8mL Light blue top - 3.2% Sodium Citrate.
Volume: 1.0 mL plasma
Minimum Volume: 1.0 mL plasma
Temperature: Room Temperature for Light blue top tube, must be received within 4 hours of draw. Plasma aliquot(s) must be frozen if not received by lab within 4 hours of collection.
Stability: Room temperature: 4 hours, Frozen: -70° C for one month
Reasons for Rejection: Clotted sample, incorrectly filled tubes, incorrect tube type, grossly hemolyzed sample, grossly lipemic sample, grossly icteric sample, whole blood >4.0 hours old
Days Performed: Monday - Friday
Times Performed: 8:00 AM. - 3:00 PM.
TAT: 1 - 3 days
Significance: Assay result is dependent on patient's level of Antithrombin. Other factor Xa inhibitors (direct and indirect) will interfere with the assay.
Special Instructions: Deliver to lab immediately. Tubes must be filled to indicator line and not clotted. Indwelling lines should be flushed with saline only and 5 mL of blood should be discarded prior to collecting samples for coagulation studies. If sending plasma aliquots, DOUBLE CENTRIFUGE plasma samples to produce platelet poor plasma. Samples received from an outside lab must be aliquoted and frozen. Grossly hemlyzed, icteric or lipemic samples may be rejected. Ordering physician name and telephone contact information MUST accompany the sample and request. Vanderbilt Esoteric Coagulation Laboratory: 615 875-5633
Search Help
Search Options for the Test Directory:
1. Enter the test name in the Keyword search field.
Hint: You can also enter any part of the test name to expand the search.
(Example: you can type "west" or "sed" or "rate" to find Westergren Sedimentation Rate)
2. Enter the Vanderbilt Test Code, if known.
3. Choose one of the letter boxes to display a list of all test names and keywords starting with that letter.
If you are unable to find a test in our directory, please contact VPLS at
1-800-551-5227 or e-mail emily.k.thompson@vumc.org.