CausesBy Mayo Clinic staff
A number of infections and diseases can contribute to an enlarged spleen. The effects on your spleen may be only temporary, depending on how well your treatment works. Contributing factors include:
- Viral infections, such as mononucleosis
- Bacterial infections, such as syphilis or an infection of your heart's inner lining (endocarditis)
- Parasitic infections, such as malaria
- Cirrhosis and other diseases affecting the liver
- Various types of hemolytic anemia — a condition characterized by premature destruction of red blood cells
- Blood cancers, such as leukemia, and lymphomas, such as Hodgkin's disease
- Metabolic disorders, such as Gaucher's disease and Niemann-Pick disease
- Pressure on the veins in the spleen or liver or a blood clot in these veins
How the spleen works
Your spleen is tucked under your rib cage next to your stomach on the left side of your abdomen. It's a soft, spongy organ that performs several critical jobs and can be easily damaged. Among other things, your spleen:
- Filters out and destroys old and damaged blood cells
- Plays a key role in preventing infection by producing white blood cells called lymphocytes and acting as a first line of defense against invading pathogens
- Stores red blood cells and platelets, the cells that help your blood clot
- May act as an intermediary between your immune system and your brain, leading researchers to speculate that they may one day be able to trigger the spleen's infection-fighting abilities by manipulating the nervous system
An enlarged spleen affects each of these vital functions. For instance, as your spleen grows larger, it begins to filter normal red blood cells as well as abnormal ones, reducing the number of healthy cells in your bloodstream. It also traps too many platelets. Eventually, excess red blood cells and platelets can clog your spleen, interfering with its normal functioning. An enlarged spleen may even outgrow its own blood supply, which can damage or destroy sections of the organ.
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