Antithrombin III Deficiency

What is Antithrombin III Deficiency?

Antithrombin III deficiency is a rare blood disorder that affects how your body controls clotting. Antithrombin III is a protein in your blood that helps prevent clots from forming when they should not. It works like a natural brake on your clotting system.

When you have low levels of this protein, your blood can clot too easily. This puts you at higher risk for dangerous clots in your veins, especially in your legs and lungs. Some people inherit this condition from their parents, while others develop it later in life.

The condition can be mild or severe depending on how low your antithrombin III levels are. Many people do not know they have it until they develop a blood clot or a family member is diagnosed. Early detection helps you take steps to prevent serious clotting events.

Antithrombin III Antigen

Checks blood's clotting ability
Measures clot-preventing protein levels
Evaluates risk of blood clots

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Symptoms

Deep vein thrombosis, blood clots in leg veins that cause pain and swelling
Pulmonary embolism, blood clots in the lungs that cause chest pain and breathing trouble
Recurrent miscarriages or pregnancy complications
Blood clots at younger ages, typically before age 50
Clots in unusual locations like the abdomen or brain
Family history of blood clots
Clots without clear triggers like surgery or injury

Many people with antithrombin III deficiency have no symptoms until they develop their first blood clot. Some never experience clotting problems at all, especially if they have mild deficiency.

Causes and risk factors

Antithrombin III deficiency can be inherited or acquired. The inherited form comes from genetic mutations passed down from parents. You only need one mutated gene from one parent to develop the condition. The acquired form develops due to other health conditions or situations that lower antithrombin III levels.

Risk factors for acquired deficiency include liver disease, kidney disease with protein loss, severe infections, major surgeries, estrogen therapy or birth control pills, and pregnancy. Certain blood thinners can also temporarily lower antithrombin III levels. If you have a family history of early blood clots or recurrent clots, you may have inherited this condition.

How it's diagnosed

Doctors diagnose antithrombin III deficiency with specialized blood tests that measure antithrombin III levels and activity. The Antithrombin III Antigen test checks how much of this protein is in your blood. Testing is usually done after a blood clot occurs or if you have a strong family history of clotting disorders.

Your doctor may order testing if you develop blood clots at a young age, have recurrent clots, or have clots in unusual locations. Blood testing should not be done while you are actively taking blood thinners or during an acute clotting event, as results may not be accurate. Talk to our medical team about testing options and whether specialized testing is right for you.

Treatment options

Blood thinning medications like warfarin or heparin to prevent new clots
Antithrombin concentrate infusions for severe deficiency or during high-risk situations
Avoiding estrogen-containing birth control pills and hormone therapy
Staying active and avoiding long periods of sitting or bed rest
Wearing compression stockings during flights or long travel
Maintaining a healthy weight through balanced nutrition
Staying well hydrated to support healthy blood flow
Genetic counseling if you plan to have children
Extra monitoring and prevention during pregnancy and surgery

Frequently asked questions

Antithrombin III is a natural protein in your blood that prevents excessive clotting. It works by blocking certain clotting factors that would otherwise cause your blood to form clots. When levels are too low, your blood becomes more likely to clot when it should not, leading to dangerous blockages in your veins.

Most people discover they have this condition after developing a blood clot or when a family member is diagnosed. Symptoms include blood clots in the legs or lungs, especially at younger ages. Your doctor can diagnose the condition with a blood test that measures antithrombin III levels and activity.

Yes, the inherited form is passed down from parents through genes. You only need to inherit one mutated gene from one parent to develop the condition. However, some people develop acquired deficiency later in life due to other health conditions like liver disease or kidney problems.

There is no cure for inherited antithrombin III deficiency. However, it can be managed effectively with blood thinning medications and lifestyle changes. Acquired deficiency may improve if the underlying condition causing it is treated successfully.

The main risk is developing dangerous blood clots in your veins. These clots can occur in your legs, lungs, or other parts of your body. Women with this condition also face higher risks during pregnancy, including miscarriage and pregnancy complications.

It depends on your individual situation and clotting history. Some people need lifelong blood thinners after their first clot, while others may only need them during high-risk periods like surgery or pregnancy. Your doctor will create a treatment plan based on your specific risk factors and medical history.

Yes, many people with this condition have healthy pregnancies with proper medical care. You will need close monitoring and likely blood thinning medication during pregnancy and after delivery. Working with specialists experienced in high-risk pregnancies is important for the best outcomes.

Avoid estrogen-containing birth control pills and hormone therapy, as they increase clotting risk. Try to avoid long periods of inactivity, staying well hydrated, and maintaining a healthy weight. Always inform doctors and dentists about your condition before procedures or surgeries.

Testing frequency depends on your treatment plan and whether you have had clotting events. Your doctor may retest to confirm diagnosis or monitor treatment effectiveness. Regular testing is not usually needed once you are on stable treatment.

Yes, lifestyle changes can reduce your clotting risk alongside medical treatment. Stay active with regular movement, maintain a healthy weight, drink plenty of water, and avoid smoking. Wearing compression stockings during travel and avoiding long periods of sitting also help prevent clots.