Anti Xa UFH | KK Women's and Children's Hospital

Specimen Container

3.2% Sodium Citrate Tube

Specimen Requirement

Citrated Whole Blood

Adult: 2 mL

Paediatric and Neonate: 1 ml

- Gently invert the tubes several times to prevent clotting. Clotted specimen is not suitable for testing.

- To collect blood to the designate marking. Over or under filling will compromise the test results.

- When using a winged blood collection set for venipuncture and a coagulation tube is the first tube drawn, draw a discard tube first.

- When obtaining specimens from indwelling lines that may contain heparin, the line should be flushed with 5mL of saline; and the first 5mL of blood or 6-times the line volume (dead space volume of the catheter) be drawn off and discarded before the coagulation tube is filled.

- For those samples collected from a normal saline lock (capped off venous port) twice the dead space volume of the catheter and extension set should be discarded.

Specimen Storage/Transport

Send to laboratory as soon as possible after blood collection. Do not send in ice.

Orderable as Urgent?

Turn Around Time

Routine: 2 - 3 hrs

Urgent tests requiring a shorter turnaround time can be requested by contacting the laboratory haematologist-on-call.

Reference Value(s)

Therapeutic range: 0.3 - 0.7 IU/mL

Therapeutic ranges adopted from KKH Adult and Paediatric Anticoagulation Guidelines and Enoxaparin Prescribing Information.

Testing Laboratory Location

KKH

Laboratory

Haematology

Contact Number

6394 1373

Day and Time Performed

Mon – Fri: 0800 hrs– 1700 hrs

Orderable on CPOE?

Yes. The correct type of Anti-Xa test (LMWH or UFH) must be requested in the CPOE order according to the heparin in use. The Laboratory or Clinical Haematologist may be consulted for advice if required.

Downtime Form

63170-Form-1080 Haematology Laboratory Downtime Form

Additional Information

Approval from Haematologist is required for test request after operating hours.

Coloured plasma may interfere with chromogenic testing. Samples which are haemolysed, lipaemic or icteric will be rejected.

Change History Notes

16 Sep 2024 08:00 AM

Updated Specimen Container, Orderable as STAT?, Turn Around Time.
15 Feb 2023 12:00 AM

Updated Additional Information.
06 Feb 2023 12:00 AM

Updated Specimen Storage / Transport, Reference Value(s), Laboratory, Orderable on CPOE, Downtime Form.
21 Oct 2022 12:00 AM

Updated Specimen Requirement, Specimen Storage / Transport.

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Last Updated - 27 May 2025