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HelpTest Code RIVAR Rivaroxaban, Anti-Xa, Plasma
Ordering Guidance
This assay is not indicated for monitoring low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH) concentrations. The presence of UFH and LMWH will cause the rivaroxaban anti-Xa level to be falsely elevated.
This assay is optimized to measure rivaroxaban concentration in presence of coagulation factor Xa recombinant, inactivated-zhzo (andexanet alfa, Andexxa).
Necessary Information
Specimen Required
Specimen Type: Platelet-poor plasma
Collection Container/Tube: Light-blue top (3.2% sodium citrate)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Specimen should be collected 2 to 4 hours (peak) after a dose or just prior (trough) to the next dose for rivaroxaban concentrations.
2. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing
3. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.
4. Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom of centrifuged vial.
5. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally, below -40 C degrees.
Additional Information:
1. A 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.
Useful For
Measuring rivaroxaban concentration in selected clinical situations (eg, kidney insufficiency, assessment of compliance, periprocedural measurement of drug concentration, suspected overdose, advanced age, and extremes of body weight)
Special Instructions
Method Name
Chromogenic Assay
Reporting Name
Rivaroxaban, Anti-Xa, PSpecimen Type
Plasma Na CitSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Na Cit | Frozen | 42 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Clinical Information
Rivaroxaban, an oral anticoagulant that directly inhibits factor Xa, has been approved by the US Food and Drug Administration for prophylaxis of thrombosis in atrial fibrillation and surgical patients and treatment of venous thromboembolism (VTE). Unlike warfarin, it does not require routine therapeutic monitoring. However, in selected clinical situations, measurement of drug level would be useful (eg, kidney insufficiency, assessment of compliance, periprocedural measurement of drug concentration, suspected overdose, advanced age, and extremes of body weight).
Table. Plasma Concentrations of Rivaroxaban in Patient Populations Studied(1)
|
Patient population/clinical setting |
Rivaroxaban dose |
C-min (ng/mL)* |
C-max (ng/mL)** |
|
VTE prevention after total hip replacement surgery |
10 mg once daily |
9 (1-38) |
125 (91-196) |
|
DVT treatment (continued treatment) |
20 mg once daily |
26 (6-87) |
270 (189-419) |
|
Stroke prevention in patients with non-valvular AF (CR-CL ≥50 mL/min) |
20 mg once daily |
44 (12-137) |
249 (184-343) |
|
Stroke prevention in patients with non-valvular AF (CR-CL 30-49 mL/min) |
15 mg once daily |
57 (18-136) |
229 (178-313) |
|
Secondary prevention in patients with acute coronary syndrome |
2.5 mg twice daily |
17 (6-37) |
46 (28-70) |
Median (5th-95th percentile)
*Defined as samples collected 20-28 hours after dosing
**Defined as samples collected 2-4 hours after dosing
Abbreviations not previously defined:
Atrial fibrillation (AF)
Creatinine clearance (CR-CL)
Deep vein thrombosis (DVT)
Reference Values
An interpretive report will be provided.
Interpretation
The lower limit of detection of this assay is 4 ng/mL.
Therapeutic reference ranges have not been established. See Clinical Information section for peak and trough drug concentrations observed from clinical trials.
Cautions
Routine monitoring of rivaroxaban is not indicated. Therapeutic reference ranges have not been established, however, peak and trough levels observed in clinical trials at different dosing are available. Rivaroxaban concentration may be affected by drug interactions and liver or kidney disease.
Method Description
The rivaroxaban, anti-Xa assay is performed on the Instrumentation Laboratory ACL TOP Family using the HemosIL Liquid Anti-Xa kit. The liquid Anti-Xa kit is a 1-stage chromogenic assay based on a synthetic chromogenic substrate and on factor Xa inactivation. Factor Xa is neutralized directly by rivaroxaban. Residual factor Xa is quantified with a synthetic chromogenic substrate. The para-nitroaniline released is monitored kinetically at 405 nm and is inversely proportional to the rivaroxaban in the sample.(Package insert: HemosIL Liquid Anti-Xa kit. Instrumentation Laboratory Company; REV 06/2017)
Day(s) Performed
Monday through Friday
Report Available
1 to 3 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
80299LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| RIVAR | Rivaroxaban, Anti-Xa, P | 74871-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| RIVA1 | Rivaroxaban, Anti-Xa, P | 74871-5 |
| RIVA2 | Interpretation | 69049-5 |
| RIVA3 | Cautions | 62364-5 |