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Clotting inhibitors or anticoagulants; antithrombin III, antigen assay

CPT4 code

Name of the Procedure:

Clotting Inhibitors or Anticoagulants; Antithrombin III, Antigen Assay


The Antithrombin III, Antigen Assay is a blood test used to measure the level of antithrombin III, a protein in the blood that helps regulate blood clotting.


The procedure is used to diagnose potential clotting disorders or deficiencies in antithrombin III. The goal is to identify abnormalities that could lead to excessive clotting or bleeding issues.


  • Unexplained blood clots
  • Family history of clotting disorders
  • Recurrent miscarriages
  • Unexplained prolonged bleeding
  • Patients undergoing anticoagulant therapy


  • Typically, no fasting is required.
  • Medication adjustments may be necessary; patients should consult their physician.
  • Inform the healthcare provider of any medications or supplements being taken.

Procedure Description

  1. A healthcare professional will draw a blood sample from a vein in the arm.
  2. The sample is then sent to a laboratory for analysis.
  3. Laboratory technicians use immunoassay techniques to measure antithrombin III antigen levels in the blood.


The blood draw itself takes about 5-10 minutes. Results are usually available within a few days to a week.


Performed in a hospital, outpatient clinic, or diagnostic laboratory.


  • Phlebotomists or nurses to draw blood.
  • Laboratory technicians to analyze the sample.
  • Physicians to interpret the results.

Risks and Complications

  • Minimal risk of infection at the puncture site.
  • Possible bruising or discomfort at the site where blood is drawn.


  • Accurate diagnosis of clotting disorders or antithrombin III deficiencies.
  • Enables appropriate treatment plans to prevent complications like thrombosis or excessive bleeding.


  • No specific recovery time; patients can resume normal activities immediately after the blood draw.
  • Follow-up with a physician for interpretation of results and further management.


  • Other coagulation tests such as Protein C and Protein S assays.
  • Genetic testing for clotting disorders.
  • Pros: Comprehensive clotting profile; Cons: May require multiple tests and longer turnaround for results.

Patient Experience

  • Minor discomfort during the blood draw.
  • No significant pain or recovery time required.
  • Clear communication from healthcare providers regarding results and next steps helps ensure patient comfort and understanding.

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