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22333 Antithrombin III, Functional

Antithrombin III, Functional
Test Code: ATIII
Synonyms/Keywords
​AT III, Antithrombin III Activity, Anti-thrombin
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​*Platelet Poor ​Plasma 3.2% Citrated Blue Top Tube (BTT)​ ​ 0.75 mL ​ 0.75 mL ​ 0.5 mL ​
Collection Processing Instructions
One 0.75 mL citrated (BTT) plasma aliquot.
If more than one coagulation test is ordered, a separate aliquot is needed for each test. 
- Collect in Citrated Blue Top Tube (BTT)
- Citrate anticoagulant must be adjusted for HCT >55%.
- Tube must be at least 90% full.
- Invert completely 3-4 times (without shaking) to mix.
 *See Instructions for: Preparation of Platelet Poor Plasma
Specimen Stability Information
Specimen Type Temperature Time
​Plasma ​Frozen ​6 months
Rejection Criteria
Clotted or Hemolyzed
​Contamination with IV or Hickman Line fluids
​Specimens that thaw during storage or transport
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Marshfield ​ Monday through Friday ​Less than 2 hours Chromogenic/Siemens BCSXP​
Test Information
See Clinical Practice Guidelines for more information
Reference Range Information
Performing Location Reference Range
​Marshfield ​80-120%
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​85300 ​ ​ ​
Synonyms/Keywords
​AT III, Antithrombin III Activity, Anti-thrombin
Ordering Applications
Ordering Application Description
​COM ​Antithrombin III Functional
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​*Platelet Poor ​Plasma 3.2% Citrated Blue Top Tube (BTT)​ ​ 0.75 mL ​ 0.75 mL ​ 0.5 mL ​
Collection Processing
One 0.75 mL citrated (BTT) plasma aliquot.
If more than one coagulation test is ordered, a separate aliquot is needed for each test. 
- Collect in Citrated Blue Top Tube (BTT)
- Citrate anticoagulant must be adjusted for HCT >55%.
- Tube must be at least 90% full.
- Invert completely 3-4 times (without shaking) to mix.
 *See Instructions for: Preparation of Platelet Poor Plasma
Specimen Stability Information
Specimen Type Temperature Time
​Plasma ​Frozen ​6 months
Rejection Criteria
Clotted or Hemolyzed
​Contamination with IV or Hickman Line fluids
​Specimens that thaw during storage or transport
Reference Range Information
Performing Location Reference Range
​Marshfield ​80-120%
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Marshfield ​ Monday through Friday ​Less than 2 hours Chromogenic/Siemens BCSXP​
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​85300 ​ ​ ​
For most current information refer to the Marshfield Laboratory online reference manual.