Blood Disorders That Lead to Stroke

A stroke is brain damage caused by interruption of blood flow to the brain. Most of the time, this is a result of the restriction of the normal, smooth flow of blood due to damaged blood vessels in the brain, the heart or the neck. Blood vessels become damaged due to long-term problems such as smoking, diabetes, and hypertension. In addition, high cholesterol and triglycerides in the blood tend to stick to the wall of arteries, resulting in narrowing of these blood vessels and leading to occlusion, with interruption of blood flow in the brain, causing a stroke.

Blood cells illustration
Sebastian Kaulitzki / Science Photo Library / Getty Images

Strokes can also occur due to occlusion of blood vessels in the brain from clots originating in the heart.

However, sometimes a defect involving a person's blood is the reason for a stroke. Blood clotting diseases make a person more prone to forming blood clots, leading to ischemic strokes. Bleeding disorders cause excessive bleeding, which can lead to hemorrhagic strokes. Most of the blood disorders that lead to stroke are hereditary, and medications cause a few. Find out more about the most common blood disorders that lead to stroke.

Sickle Cell Disease 

Sickle cell disease is one of the most common hereditary blood disorders. It is a disease that causes a condition called 'sickling' of the red blood cells. Sickling is when a red blood cell suddenly changes from its normal, rounded shape and, instead, transforms into an unusual, jagged shape.

When a person with sickle cell disease experiences an illness or an infection, this can trigger a sickle cell crisis in which the red blood cells sickle and have a tendency to form blood clots. People with sickle cell disease are 2-3x more likely to experience a stroke than people who do not have sickle cell disease. Also, a person with sickle cell disease is more likely to experience a stroke at a younger age than people who do not have sickle cell disease.

Most people with sickle cell disease are diagnosed during childhood, and usually, are aware that they have the disease years before ever having a stroke. If you have sickle cell disease, the most effective way to prevent a stroke is to prevent a sickle cell crisis, which is a lifelong challenge.

Sickle cell disease is a hereditary disease. It is an X-linked recessive disorder, which means that if a person has one X chromosome that codes for the disorder and another X chromosome that does not code for the disorder, the individual is not expected to have the disease. Since, males have only one X chromosome, if that X chromosome codes for sickle cell disease, then the young man would have the disease. On the other hand, a female has 2 X chromosomes, so if one of her X chromosomes codes for sickle cell disease and the other X chromosome does not code for the disease, the woman will not have the full effects of the disease. 

Blood Clotting and Protein Abnormalities 

Blood clotting is a complex physiological response to bleeding. When you have an injury, your body forms blood clots to prevent blood loss. For example, whenever you have an open cut, your body makes a blood clot to stop the bleeding. This requires several proteins and hormones that act fairly quickly. Sometimes, the proteins involved in forming blood clots can overreact or underreact. This is usually due to one of the genetic blood disorders. 

The most common genetic diseases that cause excessive blood clot formation include the following:

  • Acquired hyperhomocysteinemia
  • Protein C or S deficiency
  • Factor V Leiden mutation 
  • Methyl-tetrahydro-folate-reductase (MTHFR)
  • C677T mutation 
  • Anticardiolipin antibodies 
  • Lupus anticoagulant 
  • Thrombocytosis  
  • G20210A prothrombin gene mutation
  • Fibrinogen abnormality

All of these blood-clotting problems are rare. However, when someone has an unexplained stroke without an obvious risk factor, particularly when the person is young, a blood clotting disorder may be the cause of the stroke. Most regular medical labs are not equipped for the specialized testing involved with these diseases, and the test results for blood clotting diseases often take a long time to return. Many of these blood-clotting disorders are familial, so, as part of the evaluation for these rare blood clotting diseases, your doctor may ask whether you have a family history of unusual blood clots, or whether you have had circulation problems.

Bleeding Problems 

Bleeding problems make it hard for your body to create a healthy blood clot. If you have a bleeding disorder, you might bleed for longer than expected after getting a cut. Some of the blood disorders that cause excessive bleeding are called hemophilia. Bleeding in the brain is a rare complication of some inborn bleeding disorders. These disorders are characterized by a deficiency in one or more of the proteins that your body needs to form a healthy blood clot.

It is rare to have one of these bleeding problems, and even among people who have these diseases, it is rare to have a hemorrhagic stroke as a result. The bleeding deficiencies associated with hemorrhagic stroke include severe FV, FX, FVII, and FXIII deficiencies. Your doctor might order tests for one or more of these problems if you have a sudden, unexplained hemorrhage (bleed) in the brain. Sometimes, your doctor may first order a test for prothrombin time (PT) or partial thromboplastin time (PTT) or ‘bleeding time’ to see if you have a bleeding problem that prevents your blood from clotting effectively.


Cancer affects the body in several ways. One of those ways is by making the blood more prone to forming excessive blood clots. People with cancer are prone to blood clots that can result in pulmonary embolism and strokes. People with cancer have approximately a 20 percent increased risk of stroke. This can be a consequence of chemotherapy, but cancer itself can make the body more prone to having a stroke.

It is unusual for someone who has cancer to have a stroke before cancer is diagnosed. However, when someone has an unexplained stroke, the medical team may test for cancer to see if that could be the explanation for the unexplained stroke. If you have an unexplained stroke, often called a cryptogenic stroke, you might have several blood tests to see if there is a medical explanation for the cryptogenic stroke, such as a blood disorder or cancer. 

Blood Thinner Side Effects

Blood thinners are medications used to prevent blood clots. Bleeding is one of the most common side effects of blood thinners. While it is not common for blood thinners to cause bleeding in the brain, it can occur as a complication of blood thinners. This is called a hemorrhagic stroke, and it is more likely to happen when the dose of a blood thinner is too high. 

Hormone Therapy

Birth control pills and estrogen-based or testosterone-based hormone replacement therapy have been associated with an increased chance of having blood clots, including strokes. The risk of having a stroke as a result of birth control pills is quite low, although the combination of smoking and birth control pills raises that risk. The relationship between hormone replacement therapy and stroke is quite complicated.

Vitamin or Herb Overdose

There are a few vitamins and herbs that can affect blood clotting, resulting in an ischemic stroke or hemorrhagic stroke. Most notably, vitamin K, a natural component of green leafy vegetables, assists in normal, healthy blood clotting. Overdosing on vitamin K, through the use of pills or injections can cause dangerous blood clots. Some herbs such as gingko and ginger may cause excessive blood thinning, particularly in people who already take blood thinners such as aspirin. It is best to maintain moderation when taking vitamins and herbs.

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