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Laboratory Test Reference Guide

Laboratory Information

Test Name

Anti-10a Assay


Heparin assay
Clexane assay
Rivaroxaban assay

External Price (excl. GST)



Specimen Collection

Pre Testing Requirements

Samples should be taken 3-5 hours post-dose (subcutaneous LMWH), 4 hours post-dose (Rivaroxaban)

Adult Specimen

2.7 mL sodium citrate tube (light blue)

Paediatric Specimen

1.8 mL paediatric sodium citrate tube (light blue)

Instructions for Referral to Waikato Lab

Aliquot Instructions

500uL double spun platelet poor plasma

Aliquot Transport

Send frozen

Test Information



Test Availability

Mon - Sun, 24hrs

Diagnostic Use Or Instructions

Clexane: The evidence base for Target Range is poor, but the consensus for PROPHYLAXIS is 0.1-0.4 U/mL, and for TREATMENT is 0.6-1.0 U/mL (the latter applies to bd dosing; a higher target range may be appropriate for daily dosing).

Rivaroxaban: There is no established therapeutic range for Rivaroxaban (Xarelto). Plasma Rivaroxaban concentration drops after dose administration and the assay result has to be interpreted in the context of the last doses. Note that routine Rivaroxaban monitoring is not recommended and the levels should not be used for tailoring doses.

ASTH (2013) recommends the following mean peak and trough levels for 20mg once daily (od):

  Peak Trough
20mg od 170-400 ug/L 1-150 ug/L

Minimum Volume

500uL double spun platelet poor plasma

Electronic Information

Registration Code

FXA - Clexane, FXAR - Rivaroxaban

HL7Mapping Code