Enlarged Spleen (Splenomegaly)

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What is the spleen, and what is its function?

The spleen is an important organ in the body that has a variety of responsibilities.

  • It is a major filter of blood, helping remove old and damaged red blood cells, and bacteria.
  • It also part of the lymphatic system and produces lymphocytes, a type of white blood cell that is part of the immune system that helps prevent and fight infection.
  • The spleen also acts as a reservoir for red blood cells and platelets, should the body need them.

What does the spleen look like, and where is it located in the body?

The spleen is located in the left upper quadrant of the abdomen, just beneath the diaphragm and next to the stomach. It has a very rich blood supply since it is responsible for filtering blood, and it is protected by the 9th, 10th, and 11th ribs. Normally, it is the size of an orange or a small fist.

The spleen has two types of tissue; the red pulp is responsible for filtering blood, while the white pulp is responsible for its immune function.

What are the causes of an enlarged spleen?

The spleen will enlarge when it performs more of its duties to filter blood or to manufacture blood cells. Therefore, any disease or condition that damages red blood cells, and requires them to be filtered and removed from the blood stream, will cause the spleen to become larger.

Blood disorders

Conditions such as hemolytic anemia, where red blood cells are damaged and broken down (hemolyzed) can cause the spleen to enlarge. Misshapen red blood cells, like those produced in sickle cell anemia, thalassemia, and spherocytosis; may not be able to maneuver through small capillary blood vessels and then become damaged. The damaged cells need to be culled and filtered by the spleen.

Decreased blood flow

The spleen will enlarge if there is a decrease in blood flow through the splenic vein. This may cause spleen congestion and enlargement. This situation may be associated with liver disease and portal hypertension. Damage to liver cells makes it difficult for blood to flow normally, and as blood backs up in the portal vein system, it may also affect pressure in the splenic vein. This increased pressure decreases blood draining from the spleen and causes it to become congested and larger. People with congestive heart failure may have an enlarged liver and spleen because of poor blood flow to and from the heart.

Cancer

Leukemia and lymphoma may be associated with abnormal white cells that can invade the spleen and increase its size.

Metabolic diseases

Certain metabolic diseases may cause the spleen to enlarge, including Hurler Syndrome, Gaucher Disease and Niemann-Pick Disease.

Infection

Some viral infections may cause splenomegaly including:

Picture of the spleen
Picture of the spleen
Medically Reviewed by a Doctor on 4/3/2014

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