Autoimmune hemolytic anemia (AIHA) occurs when your immune system makes proteins called autoantibodies that mistakenly destroy your red blood cells (RBCs). If you’re living with this rare autoimmune disease, you may be at an increased risk of experiencing other health issues, including blood clots.

What Is a Blood Clot?

Blood clots develop when a blood vessel is injured. The clumps of blood form when platelets — cell fragments that travel throughout your bloodstream — start sticking together along with stringy proteins. These substances act as a plug, preventing all your blood from leaking out of the blood vessel.

Normally, blood clotting is helpful — it protects your body after an injury. As part of the healing process, your body usually dissolves the blood clot and forms new blood vessel tissue to patch the hole or tear.

In some cases, however, clots can cause serious problems. Blood clots may form within blood vessels when they shouldn’t or may not fully dissolve after an injury. This can prevent blood from flowing normally within your veins and arteries. If blood can’t reach a part of the body, certain organs or tissues might not receive oxygen and other nutrients carried by the blood. This can cause serious damage. When problematic blood clots form, the condition is known as thrombosis or venous thromboembolism (VTE).

AIHA and the Risk of Blood Clots

People with AIHA tend to get blood clots more often than those who don’t have this disease. One reason for this increased vulnerability may be that AIHA sometimes requires hospitalization, especially among older adults, and hospital stays raise your risk of blood clots.

Among groups of people who need to be hospitalized, blood clots are more common in those with AIHA. One study found that people hospitalized with AIHA were about three to four times more likely to experience blood clots compared with those admitted for reasons other than immune-mediated diseases. In particular, people are 11 times more likely to experience a blood clot in their lungs within one year after being hospitalized for AIHA. Having another condition such as rheumatoid arthritis or systemic lupus erythematosus in addition to AIHA also raises the chance of developing blood clots, noted an article based on a case report in the journal TH Open.

Overall, researchers estimate that 15 percent of people with AIHA develop blood clots — which means that the majority of those with the condition will never experience this problem. Still, blood clots can occur in both warm and cold types of AIHA, with other factors increasing the risk.

Other Blood Clot Risk Factors

You might be at risk of forming a blood clot if you recently had a lengthy period of inactivity (such as a long car trip or flight), seriously injured a muscle or bone, or had major surgery. Certain other conditions or characteristics may also increase your chances of a blood clot. You may be at higher risk if you:

• Are 55 or older
• Smoke cigarettes or vape (use e-cigarettes)
• Are of higher weight
• Spend most of your day sitting, especially if you often cross your legs
• Use a wheelchair
• Have family members who had blood clots
• Have certain health conditions, including diabetes, heart disease, or lung problems
• Have high blood pressure or high cholesterol levels
• Use medications or therapies that contain estrogen, including hormone therapy or birth control pills, rings, or patches
• Are pregnant or gave birth recently
• Are living with cancer
• Currently have COVID-19
• Have an inherited condition that predisposes you to blood clots

However, it’s important to know that many people with AIHA who develop blood clots do not have many or any of these risk factors. Talk to your doctor to learn more about your risk level and discuss steps you can take to protect your health.

Warning Signs of a Blood Clot

You might want to watch out for a few particular types of blood clots. Depending on where they form, blood clots can produce different symptoms.

One serious type of blood clot is deep vein thrombosis (DVT). As the name suggests, this type of blood clot forms in a vein deep within your body. A DVT usually develops in the legs but may also affect the arms. This type of blood clot may lead to:

• Swelling in one leg or arm
• Sudden pain, tenderness, or cramping
• Warmth in your leg or arm
• Reddened or bluish skin

An untreated DVT may move to another part of your body. A piece of the clot can also break off and travel to other tissues. When a blood clot moves to your lungs, it’s known as a pulmonary embolism. This condition can cause:

• Sharp chest pain that may worsen when you try to breathe deeply
• Dyspnea (sudden inability to catch your breath)
• Coughing, especially coughing up blood
• A fast heart rate

A pulmonary embolism can be a life-threatening medical emergency. Seek immediate medical care if any of these symptoms appear.

Blood clots may also lead to other symptoms. If a clot forms in the brain, it is known as a stroke. A stroke can leave you unable to move one side of your body or to talk normally, give you sudden severe headaches, or cause vision changes or seizures.

A blood clot in the heart can make you feel like you are having a heart attack. You may develop sudden chest pain or squeezing, breathing difficulties, or sweating, as well as pain in your arm, neck, or back. If a blood clot moves to tissues in your abdomen, you might have abdominal pain that comes on quickly or experience nausea or vomiting.

Preventing Blood Clots

Many of the risk factors that lead to blood clots are preventable. To help protect yourself, it’s important to educate yourself about blood clot symptoms so that you can recognize a problem right away. You may also want to take these steps to stave off blood clots:

• Get up and move around every couple of hours rather than sit for long stretches.
• Take regular breaks to stretch and move during travel.
• Drink plenty of water.
• Eat a nutritionally balanced diet.
• Achieve and maintain a healthy weight.
• Quit smoking.
• Manage conditions such as diabetes and high blood pressure.
• Ask your health care team about blood clot risk before you have surgery, and become active again as soon as possible after a procedure.

If you’re worried about the possibility of blood clots, talk to your doctor about your risk factors and ask whether you need prophylaxis (preventive treatment). For example, people at high risk of blood clots sometimes take anticoagulants (blood thinners) to help keep clots from forming. Some small studies have found that anticoagulants may also help people with AIHA avoid blood clots.

Wearing compression stockings, which put pressure on the legs, can also reduce your blood clot risk. However, make sure to speak with your health care provider before wearing compression stockings, as they do pose some potential health risks for people with certain conditions or if they’re worn incorrectly.

For those with AIHA, blood clots are most likely to develop during hemolysis — when your body is destroying your red blood cells. The following signs of active AIHA may indicate that you are at a higher risk of blood clots:

• Low levels of hemoglobin, a protein found in RBCs
• High numbers of leukocytes (white blood cells)
• High levels of lactate dehydrogenase (LDH), an enzyme found in blood cells
• High levels of bilirubin, a substance made when red blood cells are destroyed

Working with your health care team to properly manage your AIHA may help you avoid problems such as blood clotting. Make sure to attend all follow-up appointments and stick to the treatment plan your doctor recommends to keep your AIHA under control.

Talk With Others Who Understand

On myAIHAteam, members with AIHA and their loved ones come together to ask questions, give advice, and share their stories with others who understand life with this rare disease.

Have you talked to your doctor about your risk of experiencing a blood clot? Do you follow any strategies for preventing blood clots? Share your experience in the comments below, or start a conversation by posting on myAIHAteam.