What are the Causes of an Enlarged Spleen?

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About the Spleen

The spleen is an organ that works as part of the lymph system. It is located under the rib cage, in the upper left abdomen area toward the back. It helps defend the body against the threat of infection by acting as a drainage system. This drainage system eats up dead tissue, bacteria and other foreign matter that has entered the body through the bloodstream. It is basically the blood filtering system of the body.

The medical term for spleen enlargement is splenomegaly. Here are the different causes of an enlarged spleen.

Viral, Parasitic and Bacterial Infections

When a viral, parasitic or bacterial infection threatens the body, the spleen also contributes to the body’s defenses by producing white blood cells to fight off the infection. If the infection is too widespread or severe, it can trigger the spleen to work overtime. Enlargement of the spleen usually occurs when the spleen continues to work overtime for a period of time. Examples of these conditions include infectious mononucleosis, malaria and endocarditis.

Vein Blockage

Blood is delivered to the spleen via the splenic artery, then exits it via the splenic vein. This vein, if blocked, can cause blood to be trapped inside the spleen. The build up of blood in the spleen often leads to its swelling. This will also stop or slow down blood flow, which can cause deadly problems if not treated immediately. Increased venous pressure can also cause blood to build up in the spleen and lead to its swelling. Examples of conditions that may lead to vein blockage and increased venous pressure are portal vein obstruction and congestive heart failure, respectively.

Abnormal Red Blood Cells

It is the function of the spleen to remove not only old red blood cells (RBCs) but also abnormally-shaped RBCs in the circulation. When more of these abnormally-shaped cells are filtered by the spleen, it can lead to its enlargement. Examples of conditions where RBCs are of abnormal shapes include spherocytosis, thalassemia and sickle cell disease.

Other Causes

Spleen enlargement is also frequently seen in patients with cancers, like leukemia and lymphoma. Other causes include trauma, injury, infiltrative diseases, cysts, inflammatory diseases and metabolic disorders. An enlarged spleen is not usually considered a serious problem. It is generally an indication that the spleen is overworked due to some abnormalities in the bloodstream.


Commonly experienced by patients with an enlarged spleen are pain, discomfort or sensation of fullness at the left upper region of the abdomen. Some patients may complain of inability to eat large servings of food. Other symptoms include weakness, fatigue, easy bleeding, jaundice, pain in the left shoulder and anemia.


When underlying causes of an enlarged spleen are addressed, some patients may recover. Some people might need to undergo spleen removal as treatment.


WebMD: Enlarged Spleen: Causes, Symptoms and Treatment

Mayo Clinic: Enlarged Spleen (Splenomegaly)