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Test Code 2610 Unfractionated Heparin Xa Inhibition Assay

Specimen Containers and Fixatives

3.2% Sodium Citrate Blue Top Tube (2nd Tube Method)

Specimen Required

NorthShore Lab Services: draw 2.7 mL (1.0 min) blood (see CLIENT SPECIAL INSTRUCTIONS), cnetrifuge and submit frozen plasma.

Hospital Setting: submit 2.7 mL (1.0 min) of blood (see CLIENT SPECIAL INSTRUCTIONS).

Client Special Instructions

Specimen must be the 2nd tube drawn. A minimum of 2-3 mL must be drawn in the “first” tube.

Day(s) and Time(s) Performed


Daily, 8 hours

Reference Values

Therapeutic heparin range: 0.3-0.7 U/mL

Method Name

Chromogenic Assay

CPT Code Information