Congenital antithrombin III deficiency

 

Alternative Names

Deficiency - antithrombin III - congenital; Antithrombin III deficiency - congenital

Definition

Congenital antithrombin III deficiency is a genetic disorder that causes the blood to clot more than normal.

Causes

Antithrombin III is a protein in the blood that naturally blocks abnormal blood clots from forming. It helps the body keep a healthy between bleeding and clotting. Congenital antithrombin III deficiency is an inherited disease. It occurs when a person receives one abnormal copy of the antithrombin III gene from a parent with the disease.

The abnormal gene leads to low levels of antithrombin III. These low levels of antithrombin III can cause abnormal blood clots (thrombi) that can block blood flow and damage organs.

People with this condition will often have a blood clot at a young age. They are also likely to have family members who have had a blood clotting problem.  Blood clots may occur in people who do not have the common risk factors for clotting.

Symptoms

People will usually have symptoms of a blood clot, including:

  • Coughing up blood
  • Fainting
  • Shortness of breath and pain when taking deep breaths
  • Swelling of one leg

Exams and Tests

A physical exam may show:

  • Abnormal lung sounds
  • Fast breathing
  • Fast heart rate
  • Swollen foot or leg

The doctor will check for low blood level of antithrombin III. There are different methods for checking this level.

Treatment

A blood clot is treated with blood thinning medications (also called anticoagulants). How long you need to take these medications depends on how serious the blood clot was and other factors. Discuss this with your health care provider.

Outlook (Prognosis)

Most patients have a good outcome if they stay on anticoagulant medications.

Possible Complications

Blood clots can cause death. Blood clots in the lungs are very dangerous.

When to Contact a Medical Professional

See your health care provider if you have symptoms of this condition.

Prevention

There is no way to prevent it. Once a person is diagnosed with antithrombin III deficiency, all close family members should be screened.

References

Anderson JA, Weitz JI. Hypercoagulable states. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Saunders Elsevier; 2012:chap 142.

Schafer A. Thrombotic disorders: Hypercoagulable states. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 179.

Review Date: 3/3/2013
Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.

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