Test Details
Methodology
Automated (LIATEST) enzyme immunoassay (EIA)
Result Turnaround Time
2 - 3 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
This test is used for confirmation and characterization of congenital AT deficiency.
Special Instructions
If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions.
Limitations
AT testing should not be performed on patients on heparin therapy because heparin decreases plasma AT levels.6,7 AT results for individuals on warfarin therapy should be interpreted with caution because warfarin can increase levels of AT of patients with heterozygous deficiency into the normal range.7
This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.
Custom Additional Information
See Antithrombin (AT) Deficiency Profile [015594] for more clinical information.
Specimen Requirements
Specimen
Plasma, frozen
Volume
2 mL
Minimum Volume
1 mL (Note: This volume does not allow for repeat testing.)
Container
Blue-top (sodium citrate) tube
Collection Instructions
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples unless the sample is collected using a winged (butterfly) collection system. With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternative anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes.
Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.
Stability Requirements
Temperature | Period |
|---|---|
Frozen | 28 days |
Freeze/thaw cycles | Stable x3 |
Reference Range
In newborns, AT levels are lower than in adults (39% to 89%). Levels gradually reach adult ranges by six months of age.6
Storage Instructions
Freeze.
Patient Preparation
Do not draw from an arm with a heparin lock or heparinized catheter.
Causes for Rejection
Severe hemolysis; improper labeling; clotted specimen; specimen diluted with IV fluids; samples thawed in transit; improper sample type; sample out of stability
Footnotes
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 015057 | Antithrombin Antigen | 27812-7 | 015057 | Antithrombin Antigen | % | 27812-7 |
| Order Code | 015057 | |||||
| Order Code Name | Antithrombin Antigen | |||||
| Order Loinc | 27812-7 | |||||
| Result Code | 015057 | |||||
| Result Code Name | Antithrombin Antigen | |||||
| UofM | % | |||||
| Result LOINC | 27812-7 |