From the Guidelines
Low Antithrombin III (ATIII) levels can be caused by congenital or acquired deficiencies, including familial or acquired AT III deficiency, preoperative heparin treatment, extreme thrombocytosis, septicemia, and hypereosinophilic syndrome 1.
Potential Causes of Low ATIII Levels
- Congenital AT III deficiency: an autosomal-dominant transmission pattern with a prevalence of 1 in 2000 to 1 in 20 000, typically presenting with AT III levels <50% of normal and lower-extremity venous thrombosis and PE in teenagers or young adults 1
- Acquired AT III deficiency: associated with clinical situations such as preoperative heparin treatment, extreme thrombocytosis, septicemia, and hypereosinophilic syndrome 1
- Age-related factors: normal newborns and infants typically have low levels of AT III in the range of 20% to 80% of adult levels, with AT III levels approaching adult values at 6 months of age 1
Clinical Implications
Individuals with low ATIII levels may be at risk of developing thrombosis, including deep vein thrombosis (DVT) or pulmonary embolism (PE), and may require treatment with anticoagulant medications or ATIII replacement therapy 1.
Treatment Options
Treatment of heparin resistance due to AT III deficiency may include transfusion of fresh-frozen plasma or AT III concentrate, with AT III concentrate offering advantages such as diminished volume load and rapid availability 1.
From the FDA Drug Label
- 7 Heparin Resistance
Resistance to heparin is frequently encountered in fever, thrombosis, thrombophlebitis, infections with thrombosing tendencies, myocardial infarction, cancer, in postsurgical patients, and patients with antithrombin III deficiency.
The potential causes of low Antithrombin III (ATIII) levels include:
- Antithrombin III deficiency Other potential causes are not directly mentioned in the label.
From the Research
Potential Causes of Low Antithrombin III (ATIII) Levels
- Hereditary antithrombin deficiency, which is a congenital disorder that predisposes patients to thromboemboli 2
- Acquired antithrombin deficiency, which can result from various conditions such as liver dysfunction, premature infancy, sepsis, or major surgery 2
- Nephrotic syndrome, which can lead to low AT-III levels due to loss of antithrombin in the urine 3
- Critically ill patients, who may experience a decrease in AT-III levels due to the severity of their illness 4, 5
- Trauma patients, who may have a high incidence of antithrombin III deficiency due to the complexity of their coagulopathy 5
- Poor gastrointestinal absorption of warfarin, which can lead to refractory anticoagulation therapy and potentially low AT-III levels 6
Associated Conditions
- Venous thromboembolism (VTE), which is a potentially preventable complication in critically ill surgical patients and is associated with low AT-III levels 4
- Thrombosis, which can occur in patients with antithrombin III deficiency due to the imbalance of coagulation factors 6, 2
- Sepsis, which can lead to a decrease in AT-III levels and increase the risk of thrombosis 2
- Liver dysfunction, which can result in reduced plasma antithrombin levels 2