Test Name
ANTITHROMBIN III ANTIGEN
Aliases
ANTITHROMBIN, HEPARIN COFACTOR I
Abbreviations
AT, ATIII, AT III, AT-III
Test Classification
INDIVIDUAL
Department
HEMATOLOGY
Sub Department
COAGULATION
TAT Category
ELAPSED (CONTINUOUS) TIME
Estimated TAT
10
TAT Units
DAYS
Test Requirements
FROZEN, DOUBLE CENTRIFUGED CITRATED PLASMA required. Collect whole blood in citrate tube(s) filled up to the mark, centrifuge, separate plasma, centrifuge plasma, separate & FREEZE supernatant. Two 2 mL aliquots required.
Detailed guidance on preparation of platelet poor (double centrifuged) plasma can be found here: https://www.youtube.com/watch?v=9z6c8Bgr2EY
SHIPPING/ TRANSPORTATION REQUIREMENTS
Shipping Temperature: Frozen
ANALYTE STABILITY
Frozen: 1 month at -20°C
Clinical Utility
Low levels are associated with a tendency to clot.
ATIII antigen levels measure quantity of the protein whereas ATIII activity measures function of the protein.
Last Review
26th Feb 2026