Apr 1, 2015




Clinical Hub,Tools & Resources,UWHC Lab Test Directory,Coagulation

Fondaparinux Level by anti-Xa

Fondaparinux Level by anti-Xa (HCFONDA) Coagulation Lab Test

Name: Fondaparinux Level by anti-Xa

Test Name: Fondaparinux Level by anti-Xa

Health Link Test Code: HCFONDA

LIS Test Code: FONDA

CPT Code(s): 85520

Methodology: Chromogenic Anti-Xa Assay

Clinical Information:

The plasma level of Fondaparinux is determined by the measurement of anti-Xa activity.

Days Performed: Daily- Specimens are accepted at any time. Testing required during off hours must be approved by a Coagulation physician. Call (608)263-5005 before collection.

In-Lab Turnaround Time: 1 day.

Stat In-Lab Turnaround Time: 2 hours.

Specimen: Blood

Collection Container: Light blue top (3.2% NaCitrate)

Collection Instructions:

Do NOT draw through a line containing heparin as this method is unable to distinguish fondaparinux from heparin in the sample. The venipuncture MUST be atraumatic to avoid hemolysis and contamination with tissue factors and platelets.

Collection Volume: Full 3.5 mL tube

Pediatric Collection Volume: Pediatric tube filled to fill mark

Stability Ambient:

1 hour off cells

Stability Refridgerated:

Not acceptable

Stability Frozen:

2 weeks at -20°C; 6 months at -70°C

Sample Analyzed: Plasma

Testing Volume: 1 mL

Pediatric Testing Volume: 0.3 mL

Specimen Processing:

Centrifuge specimen to yield platelet poor plasma (platelet count of plasma should be less than 10K/µL). Separate plasma and transfer to plastic tube or vial. Freeze plasma at -20°C or below.

Specimen Transport:

Transport whole blood specimens at room temperature to UWHC Hospital Laboratory within 1 hour of collection. See Specimen Processing for instructions if transport criteria are not able to be met. Transport frozen plasma aliquot on dry ice to UWHC Hospital Laboratory.

Unacceptable Criteria:

Hemolyzed specimens, clotted specimens, partially filled tubes and whole blood specimens greater than 1 hour old when received by the laboratory are not acceptable.


Therapeutic range is 0.60-1.50 mg/L for fondaparinux when collected 3 hours post dosing.  Estimated prophylactic range is 0.10-0.50 mg/L.


Referenced from Depasse et. al.  "Assessment of three chromagenic and one clotting assays for the measurement of synthetic pentasaccharide fondaparinux (ArixtraTM) anti-Xa activity," Journal of Thrombosis and Haemostasis, 2004, volume 2, 346-379.


The performance characteristics of this test were validated by the UWHC Clinical Laboratories.  The U.S. Food and Drug Administration(FDA) has not approved or cleared this test; however, FDA approval or clearance is currently not required for clinical use of this test.  The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.  The UWHC Clinical Laboratories is authorized under Clinical Laboratory Improvement Amendments(CLIA) and by all states to perform high-complexity testing.

Interpretation Type: Interpretive Guidelines