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The causes of acquired antithrombin deficiency are easier to find than the hereditary deficiency. [3] The prevalence of antithrombin deficiency is estimated at ~0.02 to 0.2% of the general population, and 1-5% of patients with venous thromboembolism. [6] There is an elevated risk of thrombosis, whereby 50% patients with AT deficiency were found ...
Antithrombin (AT) is a small glycoprotein that inactivates several enzymes of the coagulation system. It is a 464-amino-acid protein produced by the liver.It contains three disulfide bonds and a total of four possible glycosylation sites. α-Antithrombin is the dominant form of antithrombin found in blood plasma and has an oligosaccharide occupying each of its four glycosylation sites.
Anti-thrombin antibodies can react with both types of thrombin in the antithrombin-thrombin complex. [1] Antibodies (IgG) against thrombin can strongly inhibit its activity. [ 2 ] Inhibitory anti-thrombin antibodies can be divided into 2 groups, those that inhibit coagulation activity and those the inhibit coagulation and amidase activity. [ 3 ]
In people without a detectable thrombophilia, the cumulative risk of developing thrombosis by the age of 60 is about 12%. About 60% of people who are deficient in antithrombin will have experienced thrombosis at least once by age 60, as will about 50% of people with protein C deficiency and about a third of those with protein S deficiency.
Reptilase time (RT) is a blood test used to detect deficiency or abnormalities in fibrinogen, [1] [2] especially in cases of heparin contamination. Reptilase, an enzyme found in the venom of Bothrops snakes, has activity similar to thrombin. Unlike thrombin, reptilase is resistant to inhibition by antithrombin III.
There have also been cases in patients with other deficiency, including protein S deficiency, [6] [7] activated protein C resistance (Factor V Leiden) [8] and antithrombin III deficiency. [ 9 ] Although the above hypothesis is the most commonly accepted, others believe that it is a hypersensitivity reaction or a direct toxic effect.
Heparin, also known as unfractionated heparin (UFH), is a medication and naturally occurring glycosaminoglycan. [3] [4] Heparin is a blood anticoagulant that increases the activity of antithrombin. [5] It is used in the treatment of heart attacks and unstable angina. [3] It can be given intravenously or by injection under the skin. [3]
Discontinuation of heparin is critical in a case of heparin-induced thrombocytopenia (HIT). Beyond that, however, clinicians generally treat to avoid thrombosis. [32] Treatment may include a direct thrombin inhibitor, such as lepirudin or argatroban. Other "blood thinners" sometimes used in this setting include bivalirudin and fondaparinux.