antithrombin III

Also found in: Dictionary, Acronyms, Encyclopedia.
Related to antithrombin III: antithrombin III test, protein C


any naturally occurring or therapeutically administered substance that neutralizes the action of thrombin and thus limits or restricts blood coagulation.
antithrombin I fibrin, referring to the capacity of fibrin to adsorb thrombin and thus neutralize it.
antithrombin III a naturally occurring inhibitor of blood coagulation; it is an α2-globulin member of the serpin group, synthesized in the liver and found in the plasma and various extravascular sites. It inactivates thrombin as well as certain coagulation factors and kallikrein. Inherited deficiency of the protein, an autosomal dominant disorder, is associated with recurrent deep vein thrombosis and pulmonary emboli. Complications from the disorder are prevented and, in conjunction with heparin, treated with a preparation of antithrombin III from pooled human plasma, administered intravenously.

an·ti·throm·bin III

a plasma α2-globulin process that inhibits thrombin and has anticoagulant activities. Deficiency [MIM*107300] is commonly inherited as an autosomal dominant trait, caused by mutation in antithrombin III gene (AT3) or chromosome 1q; this is one of the few known mendelizing disorders from which thrombotic disease occurs.


A gene on chromosome 1q23-q25.1 that encodes antithrombin III, a member of the serine protease inhibitor (serpin) family that rapidly inhibits thrombin, as well as other activated serine proteases of the coagulation system, and regulates the coagulation cascade.

Molecular pathology
SERPINC1 mutations cause antithrombin-III deficiency.

antithrombin III

Hematology A 58 kD α2-glycoprotein with a single polypeptide chain that inactivates serine proteases–thrombin and other coagulation proteins including factor Xa, IXa, kallikrein and others by an irreversible heparin-dependent reaction Function AT III dissolves blood clots that normally form within the circulation; heparin's anticoagulant activity hinges on activation of AT-III; AT-III-deficient individuals do not benefit from heparin therapy; ↓ AT-III may be a congenital AD condition, or acquired, occurring in DIC–due to 'consumption' or in liver disease–due to ↓ AT-III production, resulting in an ↑ risk of coagulation; AT III is ↓ in congenital deficiency, liver transplant, DIC, nephrotic syndrome, cirrhosis, chonic liver disease, carcinoma, mid-menstrual cycle; AT III is defective in 0.14% to 0.5% of the general population. See Hereditary thrombophilia, Recombinant human antithrombin III.
References in periodicals archive ?
The company processes the milk to a sterile powder form of antithrombin III for sale.
Tests included protein C, protein S, activated protein C resistance, factor V Leiden, anticardiolipin antibodies, antineutrophil cytoplasmic antibodies, rheumatoid factor, antithrombin III, anti-smooth muscle antibody, lupus anticoagulant panel, and prothrombin 20210G/A mutation (in women undergoing hormone replacement therapy).
Because heparin cannot bind directly to thrombin, it must bind to another substance, antithrombin III, which in turn inhibits thrombin.
Innovative Antithrombin III Diagnostic Testing Technologies and Emerging Markets
Invitation to tender: group b drugs, heparin, antithrombin iii, dalteparin
Yet bringing ATryn, an agent to regulate clotting in people with an inherited deficiency in the blood protein Antithrombin III, to market came with a cost.
The work-up should also include a prothrombin time/partial thromboplastin time and lupus anticoagulant profile in all of its manifestations; a measurement of protein C, S, and antithrombin III levels; a check for activated protein C resistance; as well as use of Markers of Coagulation and Hemostasis Activation (MOCHA) or your laboratory's equivalent in looking for prothrombin fragment 1.
Thrombotic build up of fibrin followed, likely caused by inactivation action of calcium phosphate on antithrombin III.
The researchers noted that previous research has shown tamoxifen therapy reduces homocysteine, fibrinogen, and antithrombin III levels, factors that are known to increase the risk of coronary artery disease.
3]) 375 154-345 Sedimentation rate (mm/h) 75 0-25 Serum iron ([micro]g/dl) 60 50-150 Serum transferrin (mg/dl) 230 204-345 Serum ferritin ([micro]g/L) 67 18-370 Protein C (%) 116 72-149 Protein S activity (%) 48 72-118 Protein S free (%) 43 72-128 Protein S total antigen 12 20-25 ([micro]g/ml) Antithrombin III (%) 96 75-127 Fibrinogen (mg/dl) 380 168-458 Lupus anticoagulant Negative Negative Anticardiolipin antibody Negative Negative Factor V Leiden mutation Negative Negative Homocysteine ([mu]mol/L) 6 4-17 Serum glycine ([mu]mol/L) 559 151-490 Serum glutamine ([mu]mol/L) 867 205-756 MCV, mean corpuscular volume; WBC, white blood cell.
Additional study of the other endogenous anticoagulants, including antithrombin III and activated protein C (in the absence of heparin), may be warranted, they concluded.
It's important to routinely search for these abnormalities as well as for the other leading inherited thrombophilias--factor V Leiden mutation, prothrombin gene mutations, antithrombin III deficiency, protein S deficiency and protein C deficiency--in all women with a history of venous thromboembolism who are pregnant or planning pregnancy.