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Thrombin–Antithrombin Complex Test

Published: August 9, 2026Updated: August 16, 2026

Measures a marker of thrombin activity and clot formation in blood. The slug suggests catheter-based collection, but the exact specimen and method are unclear.

Quick summary

["An elevated TAT result can indicate increased clot-forming activity in the blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
25028-2
Short code
RFA Guide Ves Cath throm adm W con vasc
Synonyms
RFA Guide Ves Cath throm adm W con vasc
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
rf-angio
CPT
86430
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

The thrombin–antithrombin complex test measures a substance formed when thrombin, a clot-forming enzyme, is bound by antithrombin, a natural clot inhibitor. It can help assess how much clot-forming activity is occurring in the blood.

Why might I need this test?

A clinician may order this test when evaluating suspected blood clots, excessive clotting, or conditions that can disturb the balance between clot formation and clot breakdown. The result is usually interpreted with symptoms, medical history, and other coagulation tests.

How is the test performed?

A blood sample is collected and tested in a laboratory using an assay designed to detect the thrombin–antithrombin complex. The compressed test name suggests that blood may be obtained through a catheter, but the exact collection method and laboratory platform should be confirmed with the ordering facility.

How do I prepare for the test?

No special preparation is usually necessary. If the specimen will be collected through a catheter, follow the facility's instructions for flushing, collection, and sample handling, and tell the healthcare team if you take anticoagulant or antiplatelet medicines.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Thrombin–Antithrombin complex (TAT)

Frequently asked questions

What does a high thrombin–antithrombin complex result mean?
It suggests that thrombin has recently been active and that more clot formation may be occurring than usual. It does not by itself prove that a blood clot is present.
Does this test diagnose a blood clot?
No. It provides information about clot-forming activity but must be combined with symptoms, imaging, and other coagulation tests to diagnose or exclude a clot.
Does the test require a catheter blood sample?
The compressed test name contains catheter wording, so catheter collection is possible. Confirm the required specimen and collection procedure with the laboratory or healthcare professional who ordered the test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy