I have a chronic disease that sometimes causes enlargement of the spleen. When I was diagnosed my doctor poked around to see if my spleen was normal. It was.
Like most people, I had no idea what the spleen does and, until recently, neither did doctors. We (meaning they, the experts) now know that the spleen is part of the lymphatic system. It is a ductless gland that has white cells called lymphocytes and macrophages that engulf and destroy bacteria, dead tissue, and foreign matter and removes all this from blood passing through. It also stores blood and, in some animals, it can provide blood when there is a sudden need for an increase in blood. This happens in the spleens of animals like horses and dogs but not humans. Athletes have tried to imitate this function of the spleen by injecting blood into their systems but the heart cannot handle the increased viscosity.
The spleen is in the upper left part of the abdomen, behind the stomach and just below the diaphragm. A normal spleen is about 7 by 5 by 2 inches large. An enlargement of the spleen, called splenomegaly, can have many causes, among them mononucleosis, malaria, leukemia, pernicious anemia, cysts, and tumors. A person with an enlarged spleen needs to be careful because a bump to the spleen may cause it to rupture and cause serious internal bleeding.
Sometimes part or all of the spleen must be removed. If only part of the spleen is removed, it may regenerate. If all is removed it won’t regenerate but many functions are taken over by other organs. Absence of the spleen increases the risk of serious infection and a series of three vaccinations are given to prevent bacterial infections of the lungs, brain lining, ear, or other organs. Children and infants without a spleen need to take antibiotics daily but adults do not need to. Adults need to see their doctor any time they have a fever and they are especially susceptible to serious infections from dog bites or scratches and from tick bites. There is also increased risk of septicemia. Everyone who has had a spleen removed should wear a medic alert bracelet.
Curiously, the spleen has worked itself into the popular language of many cultures. For example, in France spleen refers to melancholy. The word comes from the Greek. In the Talmud the spleen is associated with laughter, probably due to its connection to the humors. In the U.S. we “vent our spleen” when we are angry and need to get it out of our system.