An evaluation of antithrombin III laboratory tests

Area of Science:

• Clinical Chemistry
• Hematology
• Coagulation Science

Background:

• Antithrombin III (AT III) is a critical regulator of coagulation.
• Accurate measurement of AT III is essential for diagnosing hypercoagulable states.
• Existing laboratory tests for AT III vary in methodology and clinical utility.

Purpose of the Study:

• To evaluate three distinct laboratory assays for measuring antithrombin III (AT III).
• To compare functional AT III measurements in serum and plasma with AT III antigen levels in plasma.
• To assess the diagnostic performance of these assays in patients with suspected hypercoagulable conditions.

Main Methods:

• Evaluation of three laboratory tests: two functional AT III assays (serum and plasma) and one AT III antigen assay (plasma).
• Establishment of normal ranges using samples from 20 healthy subjects.
• Testing of 15 patient specimens from clinically suspected hypercoagulable states, including disseminated intravascular coagulation, pulmonary embolism, and pregnancy, with duplicate determinations.

Main Results:

• Two-thirds of patients with suspected hypercoagulable states exhibited antithrombin III (AT III) levels below the normal range across all three evaluated methods.
• A significant correlation was observed between decreased functional AT III activity and decreased AT III antigen levels in patients.
• The study confirmed the utility of AT III level assessment in identifying potential thrombotic risks.

Conclusions:

• All three evaluated laboratory methods demonstrated the capacity to identify reduced antithrombin III (AT III) levels in patients with hypercoagulable states.
• Functional and antigen measurements of AT III are concordant in reflecting the depleted levels observed in these clinical conditions.
• These findings support the use of AT III testing as a valuable diagnostic tool in the evaluation of hypercoagulability.