Low antithrombin III will cause the blood anticoagulation to be weakened. Causes include congenital AT-III defects, cirrhosis of the liver, etc. Treatments include medications such as heparin and surgical treatments. Antithrombin III is an important component in the anticoagulation system, with a normal value of 260-320mg/L. When the level of prothrombin decreases, it often suggests abnormalities in the body. 1. Congenital AT-III deficiency is an autosomal dominant disease with a young age of onset, and the abnormality can begin to appear at about 10 years of age. Patients are prone to venous thrombosis after trauma and surgery. 2. Cirrhosis: Severe liver diseases such as cirrhosis often lead to decreased levels of antithrombin and often correlate with the severity of the disease. Patients should go to the hospital as soon as they become unwell.