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HelpTest Code LABRIVAR Rivaroxaban, Anti-Xa
Additional Codes
| Test Name in EPIC | EPIC Test Code | Mnemonic |
|---|---|---|
| Rivaroxaban, Anti-Xa | LABRIVAR | RIVAR |
Useful For/Utility
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)
Specimen Type
3.2% Na Citrate plasma
Specimen Required
Fill Blue top tube to the etched line located just below the cap of the tube.
Additional Information:
1. Specimen should be collected 2 to 4 hours (peak) after a dose or just prior (trough) to the next dose for rivaroxaban concentrations.
Unacceptable specimens: Specimens that are short-draws, over-draws, clotted, or hemolyzed may yield incorrect results.
Specimen Stability Information
Specimens must be centrifuged and plasma separated from cells within 1 hour of collection.
1. To achieve platelet-poor plasma, spin down, remove top 2/3 of plasma, and spin plasma again in a plastic vial.*
2 Aliquot top 3/4 and place platelet-poor plasma in a plastic transport vial.*
3. Glass vials are not acceptable for processing/transport/storage.
4. Preferred specimen volume: 1 mL sodium citrate plasma
* 2 Aliquot labels will auto print at non-performing sites to double spin
Additional Information:
1. Double-centrifuged specimens are critical for accurate results as platelet contamination may cause spurious results.
If there is a delay in transport of >2 hours, send specimen frozen.
Method and Method Description
Chromogenic Assay
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)
Clinical Information
Rivaroxaban, Anti-Xa:
Therapeutic reference ranges have not been established. Target “on-therapy” ranges are based on peak and trough drug concentrations observed in clinical trials. Rivaroxaban concentration may be affected by drug interactions and liver or kidney disease.
This result should not be the sole indicator to determine the safety and effectiveness of anticoagulation. Consider dose timing, renal function, bleeding/thrombotic risk, and clinical context.
This assay is not indicated for monitoring low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH) concentrations.
| Patient population/clinical setting | Rivaroxaban dose |
C-min (ng/mL)* trough plasma concentration (predose) |
C-max (ng/mL)** peak plasma concentration (postdose) |
| 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)
Performing Laboratory
SMDC Clinical Laboratory
Day(s) Performed
Monday-Sunday
CPT Code Information
CPT: 80299
LOINC Code Information
Order and Result LOINC: 74871-5