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HelpTest Code LAB311 Antithrombin Activity, Plasma
Additional Codes
Sunquest: AT3M
Mayo: ATTF
Reporting Name
Antithrombin Activity, PUseful For
Diagnosis of antithrombin deficiency, acquired or congenital
Monitoring treatment of antithrombin deficiency disorders, including infusion of antithrombin therapeutic concentrate
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Plasma Na CitOrdering Guidance
Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason, consider ordering AATHR / Thrombophilia Profile, Plasma and Whole Blood.
Specimen Required
Specimen Type: Platelet-poor plasma
Collection Container/Tube: Light-blue top (3.2% sodium citrate)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.
2. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.
3. Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom of centrifuged vial.
4. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally at -40° C or below.
Additional Information:
1. A double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.
2. Each coagulation assay requested should have its own vial.
3. Heparin treatment may lower plasma antithrombin.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Na Cit | Frozen | 14 days |
Special Instructions
Day(s) Performed
Monday through Saturday
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
85300
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| ATTF | Antithrombin Activity, P | 27811-9 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| ATTF | Antithrombin Activity, P | 27811-9 |
Method Description
Patient plasma, containing antithrombin, is mixed and incubated with reagent containing factor Xa and excess heparin. Factor Xa activity in the reagent is rapidly inhibited by antithrombin. Residual factor Xa activity is then measured using an amidolytic activity assay. This occurs when residual factor Xa lyses chromogenic substrate N-alpha-benzyloxycarbonyl-D-arginyl-L-glycyl-L-arginine-p-nitroaniline-dihydrochloride and subsequently releases p-nitroaniline (detected at 405 nm) in a level that is inversely proportional to the amount of antithrombin in the sample. This method is based on inhibition of factor Xa and, therefore, only higher amounts of heparin cofactor II, alpha-2-macroglobulin, or alpha-1-antitrypsin will influence the assay.(Package insert: HemosIL Liquid Antithrombin. Instrumentation Laboratory Comp; 06/2017)
Report Available
1 to 3 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Method Name
Chromogenic Assay
Secondary ID
9030Forms
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.
Reference Values
Normal values: 80-130%
Normal, full-term newborn infants have lower levels (≥35-40%) that reach normal values by age 90 days. Premature infants (30-36 weeks gestation) have lower levels that reach normal values by age 180 days.