Assay

Heparin/Warfarin Ratio

Key Words

Heparin, Warfarin

Specimen Collection

3.0ml Citrate (Green lid). 1.4ml Citrate for paediatric (Green lid). Fill to mark.

Turnaround time

4 hours.

Test indications

Heparin and Warfarin dose monitoring.

Interferences

Lipaemia, haemolysis, anticoagulants, antiphospholipid syndrome. Samples will be processed up to 24 hours from the time of collection. However, samples older than 8 hours at processing may begin showing interferences due to sample degradation and should be interpreted with caution. The antibiotic oritavancin has been shown to react with certain coagulation reagents; it may artificially prolong the APTT for approximately 120 hours (5 days) post-dosage and the PT INR for approximately 12 hours post-dosage.

Reference Range

N/A

Minimum retesting interval

N/A