Medical expert of the article

Hematologist, oncohematologist

New publications

Antithrombin III

Alexey Portnov, medical expert
Last reviewed: 23.04.2024

All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.

We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.

If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.

The reference values (norm) of the content of antithrombin III in blood plasma are 80-120%.

Antithrombin III is a glycoprotein, the most important natural inhibitor of blood coagulation; inhibits thrombin and a number of activated clotting factors (Xa, XIIa, IXa). Antithrombin III forms a high-speed complex - heparin-ATIII - with heparin. The main site for the synthesis of antithrombin III is the liver parenchyma cells.

Deficiency of antithrombin III can be primary (hereditary) and secondary, associated with a particular disease or condition. Acquired deficiency of antithrombin III may be due to reduced synthesis, increased consumption or loss of protein.

Reduction of antithrombin III concentration - a risk factor for thrombosis; can develop with the following conditions and diseases:

atherosclerosis, in old age;
in the middle of the menstrual cycle, in the last months of pregnancy;
in the postoperative period;
with liver diseases (chronic hepatitis, cirrhosis of the liver, the level of antithrombin III decreases in proportion to the severity of the disease);
with acute DVS-syndrome (early and important laboratory test);
with the introduction of heparin (since antithrombin III combines with heparin, with a low content of antithrombin III, heparin therapy is ineffective);
when taking oral contraceptives and estrogens;
shock conditions in which the production of antithrombin III falls sharply in the liver and its inhibitors are activated in the blood (the most common cause of the decrease in the concentration of antithrombin III).

An increase in the concentration of antithrombin III in the blood is regarded as a risk factor for bleeding and is noted in the following cases:

with viral hepatitis, cholestasis, severe acute pancreatitis, pancreatic cancer;
with a deficiency of vitamin K;
when receiving anticoagulants of indirect action;
during menstruation.

trusted-source [1], [2], [3], [4], [5]

Translation Disclaimer: For the convenience of users of the iLive portal this article has been translated into the current language, but has not yet been verified by a native speaker who has the necessary qualifications for this. In this regard, we warn you that the translation of this article may be incorrect, may contain lexical, syntactic and grammatical errors.