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Anti Xa UFH

Test Code:



Specimen Container

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 STAT?

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

Turn Around Time

Routine: 2 - 3 hrs

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




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.

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



Anti Xa UFH CG0011

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