Spleen issues stem from a wide range of causes, including infections, liver disease, blood disorders, autoimmune conditions, physical trauma, and certain cancers. The most common result of these problems is an enlarged spleen (splenomegaly), which a healthy adult spleen measures up to about 12 cm long and weighs between 70 and 200 grams. When something goes wrong, the spleen can swell to double or triple its normal size, and in extreme cases exceed 20 cm and weigh over 1,000 grams.
Infections That Enlarge the Spleen
Viral infections are among the most frequent triggers of spleen problems, particularly in younger adults. Mononucleosis, caused by the Epstein-Barr virus, is one of the most well-known culprits. When a virus enters the body, the immune system ramps up antibody production. The spleen, which filters blood and houses large numbers of immune cells, becomes a battleground where antibody-antigen complexes accumulate. This chronic stimulation causes the spleen’s lymphoid tissue to expand, sometimes dramatically.
The mechanism is similar across many infections. In malaria-endemic regions, repeated exposure to the malaria parasite triggers a condition called tropical splenomegaly syndrome, where the same cycle of immune overstimulation and antibody buildup leads to massive splenic enlargement. Bacterial infections like endocarditis (an infection of the heart valves) and tuberculosis can also cause the spleen to swell as it works overtime to filter infected blood.
Liver Disease and Blood Flow Backup
The spleen and liver are closely connected through the portal vein, which carries blood from the digestive organs through the spleen and into the liver. When liver disease progresses, particularly cirrhosis, scar tissue makes it harder for blood to flow through the liver. This creates a traffic jam called portal hypertension, and pressure backs up into the spleen.
As resistance inside the liver increases, the body compensates by pushing more blood into the portal system, creating what researchers describe as a “local hyperdynamic state” around the spleen. The organ becomes congested with blood it can’t efficiently drain, and its lymphoid tissue enlarges and becomes overactive. Splenomegaly in cirrhosis patients is a sign that liver disease has progressed significantly and is associated with a worse prognosis overall.
Blood Disorders and Red Blood Cell Problems
The spleen’s job includes filtering out old or damaged red blood cells. In blood disorders like sickle cell disease, this filtering process can become dangerous. Sickle-shaped red blood cells are stiff and deformed, and as blood flows slowly through the spleen’s narrow passages, these cells lose oxygen and become even more rigid. They get stuck in the tiny openings they’d normally slip through to rejoin the bloodstream.
Once enough sickled cells block a draining vein inside the spleen, the obstruction cascades rapidly. More red blood cells sickle in response to sluggish flow and low oxygen, trapping an ever-growing volume of blood. This is called a splenic sequestration crisis. A large percentage of the body’s blood volume can become trapped in the spleen within hours, causing hemoglobin to drop sharply and the spleen to balloon in size. In children with sickle cell disease, about half of these crises involve signs of cardiovascular instability at the time they’re first seen, making them genuine medical emergencies.
Other blood conditions that affect the spleen include thalassemia and hereditary spherocytosis, both of which produce abnormally shaped red blood cells that the spleen filters out at a much higher rate than normal, leading to enlargement over time.
Cancer and the Spleen
Blood cancers, especially lymphomas and leukemias, frequently involve the spleen. The organ is packed with the very immune cells that these cancers arise from, making it a natural site for cancer cells to accumulate. In splenic lymphoma, abnormal B cells (a type of white blood cell) multiply within the spleen itself. These cancerous cells can sometimes be spotted on a blood test as unusual-looking cells with distinctive shapes, described as “hairy cells” or “villous lymphocytes” depending on the specific cancer type.
Primary splenic lymphoma, where the cancer originates in the spleen rather than spreading there from elsewhere, is relatively uncommon. More often, the spleen becomes involved as part of a cancer that has spread through the lymphatic system or bloodstream. In either case, the infiltration of cancer cells into splenic tissue causes the organ to enlarge progressively.
Autoimmune Conditions
When the immune system mistakenly attacks the body’s own tissues, the spleen often gets caught in the crossfire. Felty syndrome is a classic example: it’s a rare complication of rheumatoid arthritis defined by three co-occurring problems: rheumatoid arthritis itself, an abnormally low white blood cell count, and an enlarged spleen. The enlarged spleen traps and destroys white blood cells, red blood cells, and platelets at a higher rate than normal, which worsens the blood count problems. Patients can develop anemia from the spleen sequestering too many red blood cells, or bleeding problems from low platelet counts.
Lupus and other autoimmune diseases can cause spleen enlargement through similar mechanisms, as the spleen becomes overactive in filtering the antibody complexes that autoimmune conditions produce in excess.
Metabolic Storage Diseases
Some genetic conditions cause the spleen to enlarge because the body can’t properly break down certain fats or sugars. Gaucher disease is the most common of these. People with Gaucher disease lack sufficient activity of an enzyme that breaks down a specific type of fat molecule. Without this enzyme, the fat accumulates inside macrophages, a type of immune cell abundant in the spleen. These fat-laden cells, called Gaucher cells, have a distinctive “crumpled tissue paper” appearance under a microscope.
The macrophage immune cells are hit hardest because their normal job includes clearing out old blood cells, which contain high levels of the fats this enzyme is supposed to process. As Gaucher cells build up, they infiltrate the spleen, liver, and bone marrow. The spleen can become enormously enlarged, sometimes filling much of the abdomen.
Physical Trauma and Splenic Injury
The spleen is the most commonly injured organ in blunt abdominal trauma. Car accidents, sports collisions, and falls are the usual causes. Because the spleen is highly vascular (it filters about 5% of your total blood output per minute), injuries can range from minor bruising to life-threatening bleeding.
Splenic injuries are graded on a five-point scale. At the low end, a Grade I injury involves a small bruise covering less than 10% of the surface or a tear less than 1 cm deep. At the high end, a Grade V injury means the spleen is shattered or its main blood supply is torn, with active bleeding into the abdominal cavity. Lower-grade injuries can often heal on their own with monitoring, while higher-grade injuries may require procedures to stop the bleeding or, in severe cases, removal of the spleen entirely.
How Spleen Problems Feel
Many spleen issues develop gradually and cause no symptoms until the organ is significantly enlarged. When symptoms do appear, the most common is a feeling of fullness or discomfort in the upper left abdomen, sometimes extending to the left shoulder. You might feel full after eating very little because the enlarged spleen presses against the stomach.
One distinctive sign worth knowing is called Kehr’s sign: pain that radiates to the left shoulder without any shoulder injury. This happens because bleeding or swelling near the spleen irritates the diaphragm, and the nerves serving the diaphragm also connect to the shoulder area. Kehr’s sign is uncommon, but when it appears alongside abdominal pain, it’s a strong indicator of splenic rupture or significant irritation.
Other signs that may point to spleen problems include frequent infections (since the spleen helps fight bacteria), easy bruising or bleeding (from low platelet counts), and fatigue or shortness of breath from anemia if the spleen is destroying red blood cells faster than normal.
How Spleen Size Is Measured
Ultrasound is the standard way to assess spleen size. In a healthy adult, the spleen averages about 10.7 cm long, 7.4 cm wide, and 4.1 cm thick, with a volume around 174 milliliters. Men tend to have larger spleens than women: the average male spleen is about 11.3 cm long with a volume of 201 ml, while the average female spleen measures about 10.1 cm with a volume of 150 ml. In 97% of healthy people, spleen length stays at or below 13 cm.
A spleen measuring between 12 and 20 cm is classified as enlarged. Anything over 20 cm, or weighing more than 1,000 grams (five times the upper limit of normal), qualifies as massive splenomegaly. Reaching that size typically points to serious underlying conditions like blood cancers, storage diseases, or advanced portal hypertension rather than a simple infection.