Although the novel oral anticoagulants (NOAC) are attractive from many view points and their predictable pharmacokinetic dose-response curve allows fixed dosing, evaluation of anticoagulant activity might be indicated in the following circumstances:
The Kings Anticoagulation Reference centre routinely quantitatively assays the NOAC and provides interpretive advice, so that healthcare professionals are able to individualise anticoagulant therapy for their patients.
If you wish to utilise this service, please review the 'recommended times to draw NOAC samples' table below and complete the appropriate request form below (under sampling handling).
It is important that all information in the relevant form is complete.
|Scenario||Timing of drawing sample|
|Extremes of weight||Low body weight: trough activity
High body weight: peak activity
|Overdose or suspected over-anticoagulation||Anytime (time since last dose(s) should be recorded on request form)|
|Renal or liver dysfunction||Trough activity|
|Patient on concomitant interacting drugs||Trough activity|
|To confirm oral absorption||Peak activity|
|To assess adherence||Anytime (time since patients claimed last dose should be recorded on the request form)|
|Prior to surgical procedure||Anytime: ideally 24 hours pre-procedure|
Trough activity refers to sample being drawn, prior to next dose. Peak activity refers to sample being drawn 1-3 hours post dose for dabigatran and 2-3 hours for rivaroxaban.
Please download the following form and complete all information, and ask patient to attend the phlebotomy department at King's College Hospital. Please refer to the ideal sample time table above, and encourage patient to attend at the relevant time for the sample, so that an informative result is obtained.
Please download the following form and complete all information. Specific instructions on how the sample should be handled and shipped are documented on this form. Please refer to the ideal sample time table above when drawing the relevant sample(s).
Send the sample and the completed form to:
Blood Sciences Laboratory- Coagulation Lab
King's Thrombosis Centre
King's College Hospital
Results from samples received, will be sent back to the requesting professional by email.