The spleen is an oval shaped organ located on the left side of the body just under the ribcage. As part of the lymphatic system, the spleen produces white cells to fight infection. It also filters the blood, and destroys old, or abnormal red blood cells. Another function of the spleen is to store blood and platelets. A swollen spleen is usually secondary to another underlying disease.
Mononucleosis
The spleen will respond to certain viruses by producing an abundance of infection-fighting cells, causing it to swell. One such virus is the Epstein-Barr virus, which causes infectious mononucleosis. Swollen lymph nodes, a severe sore throat, and fever are typical symptoms of mononucleosis. This illness can cause fatigue that may last for months. Merck Manuals Medical Library notes that an enlarged spleen occurs in about half of all cases. Most people recover from mononucleosis without any major complications, but rupture of the spleen is a very serious potential outcome. Splenic rupture can result in major internal bleeding, and shock.
Cirrhosis
Cirrhosis is a disease whereby healthy liver tissue is slowly replaced with scar tissue. This scarring reduces blood flow through the liver, and prevents it from functioning properly. Cirrhosis can cause the spleen to swell, and become overactive as it filters increased numbers of red blood cells and platelets. Reduced levels of these cells in the blood stream can eventually lead to anemia, and bleeding problems.
Leukemia
Leukemia is a blood cancer that begins in the bone marrow. People with leukemia have an overproduction of abnormal white blood cells. The spleen must filter and collect these excessive numbers of cancerous cells. This causes it to enlarge. Leukemia patients frequently need to get transfusions of red blood cells and platelets. This too, can cause the spleen to swell, according to the MD Anderson Cancer Center.
Systemic Lupus Erythematosus
Systemic lupus erythematosus (SLE) is a chronic disorder wherein the immune system attacks its own tissues. The joints and skin are often affected, but SLE can also attack the heart, lungs, kidneys, and brain. About 10 percent of people with SLE develop enlarged spleens, according to Merck Manuals Medical Library. Some research suggests that the spleen may even have a causal role in SLE. Researchers at the University of California San Diego School of Medicine discovered that certain antibodies produced in the spleen can cause lupus-like symptoms. The study involved mice that overproduced an immune-regulating hormone in the spleen.
