If the splenomegaly underlies hypersplenism, a splenectomy is indicated and will correct the hypersplenism. However, the underlying cause of the hypersplenism will most likely remain; consequently, a thorough diagnostic workup is still indicated, as, leukemia, lymphoma and other serious disorders can cause hypersplenism and splenomegaly. After splenectomy, however, patients have an increased risk for infectious diseases.

Patients undergoing splenectomy should be vaccinated against "Haemophilus influenzae", "Streptococcus pneumoniae", and "Meningococcus". They should also receive annual influenza vaccinations. Long-term prophylactic antibiotics may be given in certain cases.

In cases of infectious mononucleosis splenomegaly is a common symptom and health care providers may consider using abdominal ultrasonography to get insight into a person's condition. However, because spleen size varies greatly, ultrasonography is not a valid technique for assessing spleen enlargement and should not be used in typical circumstances or to make routine decisions about fitness for playing sports.

Treat the underlying cause

Blood transfusion (PRBC) according to need

Corticosteroids and immunoglobulins are two commonly used treatments for warm antibody AIHA. Initial medical treatment consists of prednisone. If ineffective, splenectomy should be considered.

If refractory to both these therapies, other options include rituximab, danazol, cyclosphosphamide, azathioprine, or ciclosporin.

High-dose intravenous immune globulin may be effective in controlling hemolysis, but the benefit is short lived (1–4 weeks), and the therapy is very expensive.

Splenectomy is usually ineffective for the treatment of cold agglutinin disease, because the liver is the predominant site of sequestration. However, if the patient has splenomegaly, then the disease may respond to splenectomy. More importantly, a lymphoma localized to the spleen may only be found after splenectomy.

Although research is ongoing, at this point there is no cure for the genetic defect that causes hereditary spherocytosis. Current management focuses on interventions that limit the severity of the disease. Treatment options include:

- Splenectomy: As in non-hereditary spherocytosis, acute symptoms of anemia and hyperbilirubinemia indicate treatment with blood transfusions or exchanges and chronic symptoms of anemia and an enlarged spleen indicate dietary supplementation of folic acid and splenectomy, the surgical removal of the spleen. Splenectomy is indicated for moderate to severe cases, but not mild cases. To decrease the risk of sepsis, post-splenectomy spherocytosis patients require immunization against the influenza virus, encapsulated bacteria such as Streptococcus pneumoniae and meningococcus, and prophylactic antibiotic treatment. However, the use of prophylactic antibiotics, such as penicillin, remains controversial.

- Partial splenectomy: Since the spleen is important for protecting against encapsulated organisms, sepsis caused by encapsulated organisms is a possible complication of splenectomy. The option of partial splenectomy may be considered in the interest of preserving immune function. Research on outcomes is currently limited, but favorable.

- Surgical removal of the gallbladder may be necessary.

Patients with cold agglutinin disease should include good sources of folic acid, such as fresh fruits and vegetables, in their diet. Activities for these individuals should be less strenuous than those for healthy people, particularly for patients with anemia. Jogging in the cold could be very hazardous because of the added windchill factor.

There is no real treatment for Felty's syndrome, rather the best method in management of the disease is to control the underlying rheumatoid arthritis. Immunosuppressive therapy for RA often improves granulocytopenia and splenomegaly; this finding reflects the fact that Felty's syndrome is an immune-mediated disease. A major challenge in treating FS is recurring infection caused by neutropenia. Therefore, in order to decide upon and begin treatment, the cause and relationship of neutropenia with the overall condition must be well understood. Most of the traditional medications used to treat RA have been used in the treatment of Felty's syndrome. No well-conducted, randomized, controlled trials support the use of any single agent. Most reports on treatment regimens involve small numbers of patients.

Splenectomy may improve neutropenia in severe disease.

Use of rituximab and leflunomide have been proposed.

Use of gold therapy has also been described.

Prognosis is dependent on the severity of symptoms and the patient's overall health.

Treatment consists of frequent blood transfusions and chelation therapy. Potential cures include bone marrow transplantation and gene therapy.

The one known curative treatment is allogeneic stem cell transplantation, but this approach involves significant risks.

Other treatment options are largely supportive, and do not alter the course of the disorder (with the possible exception of ruxolitinib, as discussed below). These options may include regular folic acid, allopurinol or blood transfusions. Dexamethasone, alpha-interferon and hydroxyurea (also known as hydroxycarbamide) may play a role.

Lenalidomide and thalidomide may be used in its treatment, though peripheral neuropathy is a common troublesome side-effect.

Frequent blood transfusions may also be required. If the patient is diabetic and is taking a sulfonylurea, this should be stopped periodically to rule out drug-induced thrombocytopenia.

Splenectomy is sometimes considered as a treatment option for patients with myelofibrosis in whom massive splenomegaly is contributing to anaemia because of hypersplenism, particularly if they have a heavy requirement for blood transfusions. However, splenectomy in the presence of massive splenomegaly is a high-risk procedure, with a mortality risk as high as 3% in some studies.

In November 2011, the FDA approved ruxolitinib (Jakafi) as a treatment for intermediate or high-risk myelofibrosis. Ruxolitinib serves as an inhibitor of JAK 1 and 2.

The "New England Journal of Medicine" (NEJM) published results from two Phase III studies of ruxolitinib. These data showed that the treatment significantly reduced spleen volume, improved symptoms of myelofibrosis, and was associated with improved overall survival compared to placebo.

Asplenia is the absence of normal spleen function. It predisposes to some septicemia infections. Therefore, vaccination and antibiotic measures are essential in such cases. There are multiple causes:

- Some people congenitally completely lack a spleen, although this is rare.

- Sickle-cell disease can cause a functional asplenia (or autosplenectomy) by causing infarctions of the spleen during repeated sickle-cell crises.

- It may be removed surgically (known as a splenectomy), but this is rarely performed, as it carries a high risk of infection and other adverse effects. Indications include following abdominal injuries with rupture and hemorrhage of the spleen, or in the treatment of certain blood diseases (Idiopathic thrombocytopenic purpura, hereditary spherocytosis, etc.), certain forms of lymphoma or for the removal of splenic tumors or cysts.

Multiple blood transfusions can result in iron overload. The iron overload related to thalassemia may be treated by chelation therapy with the medications deferoxamine, deferiprone, or deferasirox. These treatments have resulted in improving life expectancy in those with thalassemia major.

Deferoxamine is only effective via daily injections which makes its long-term use more difficult. It has the benefit of being inexpensive and decent long-term safety. Adverse effects are primary skin reactions around the injection site and hearing loss.

Deferasirox has the benefit of being an oral medication. Common side effects include: nausea, vomiting and diarrhea. It however is not effective in everyone and is probably not suitable in those with significant cardiac issues related to iron overload. The cost is also significant.

Deferiprone is a medication that is given by mouth. Nausea, vomiting, and diarrhea are relatively common with its use. It is available in both Europe and the United States. It appears to be the most effective agent when the heart is significantly involved.

There is no evidence from randomized controlled trial to support zinc supplementation in thalassemia.

Usually no treatment is needed. Folic acid supplementation may help produce normal red blood cells and improve the symptoms of anemia

The most common causes of splenomegaly in developed countries are infectious mononucleosis, splenic infiltration with cancer cells from a hematological malignancy and portal hypertension (most commonly secondary to liver disease, and sarcoidosis). Splenomegaly may also come from bacterial infections, such as syphilis or an infection of the heart's inner lining (endocarditis).

The possible causes of moderate splenomegaly (spleen <1000 g) are many, and include:

The causes of massive splenomegaly (spleen >1000 g) are fewer, and include:

- visceral leishmaniasis (kala-azar)

- chronic myelogenous leukemia

- myelofibrosis

- malaria

- splenic marginal zone lymphoma

People with severe thalassemia require medical treatment. A blood transfusion regimen was the first measure effective in prolonging life.

Splenic diseases include splenomegaly, where the spleen is enlarged for various reasons. On the other hand, a lack of normal spleen function is called asplenia.

While investigational drug therapies exist, no curative drug treatment exists for any of the MPDs. The goal of treatment for ET and PV is prevention of thrombohemorrhagic complications. The goal of treatment for MF is amelioration of anemia, splenomegaly, and other symptoms. Low-dose aspirin is effective in PV and ET. Tyrosine kinase inhibitors like imatinib have improved the prognosis of CML patients to near-normal life expectancy.

Recently, a "JAK2" inhibitor, namely ruxolitinib, has been approved for use in primary myelofibrosis. Trials of these inhibitors are in progress for the treatment of the other myeloproliferative neoplasms.

Experimental gene therapy exists to treat hereditary spherocytosis in lab mice; however, this treatment has not yet been tried on humans due to all of the risks involved in human gene therapy.

Most affected individuals with pyruvate kinase deficiency do not require treatment. Those individuals who are more severely affected may die in utero of anemia or may require intensive treatment. With these severe cases of pyruvate kinase deficiency in red blood cells, treatment is the only option, there is no cure. However, treatment is usually effective in reducing the severity of the symptoms.

The most common treatment is blood transfusions, especially in infants and young children. This is done if the red blood cell count has fallen to a critical level. The transplantation of bone marrow has also been conducted as a treatment option.

There is a natural way the body tries to treat this disease. It increases the erythrocyte production (reticulocytosis) because reticulocytes are immature red blood cells that still contain mitochondria and so can produce ATP via oxidative phosphorylation. Therefore, a treatment option in extremely severe cases is to perform a splenectomy. This does not stop the destruction of erythrocytes but it does help increase the amount of reticulocytes in the body since most of the hemolysis occurs when the reticulocytes are trapped in the hypoxic environment of the spleen. This reduces severe anemia and the need for blood transfusions.

Iatrogenic causes of pancytopenia include chemotherapy for malignancies if the drug or drugs used cause bone marrow suppression. Rarely, drugs (antibiotics, blood pressure medication, heart medication) can cause pancytopenia.

The antibiotics Linezolid and Chloramphenicol can cause pancytopenia in some individuals.

Rarely, pancytopenia may have other causes, such as mononucleosis, or other viral diseases. Increasingly, HIV is itself a cause for pancytopenia.

- Familial hemophagocytic syndrome

- Aplastic anemia

- Gaucher's disease

- metastatic carcinoma of bone

- Multiple Myeloma

- overwhelming infections

- Lymphoma

- myelofibrosis

- Dyskeratosis congenita

- Myelodysplastic syndrome

- Leukemia

- Leishmaniasis

- Severe Folate or vitamin B12 deficiency

- Systemic lupus erythematosus

- Paroxysmal nocturnal hemoglobinuria (blood test)

- Viral infections (such as HIV, EBV--undetermined virus is most common).

- Alimentary toxic aleukia

- Copper deficiency

- Pernicious anemia

- Medication

- Hypersplenism

- Osteopetrosis

- Organic acidurias (Propionic Acidemia, Methylmalonic Aciduria, Isovaleric Aciduria)

- Low dose arsenic poisoning

- Sako disease (Myelodysplastic-cytosis)

- Chronic radiation sickness

- LIG4 syndrome

Salt restriction is often necessary, as cirrhosis leads to accumulation of salt (sodium retention). Diuretics may be necessary to suppress ascites. Diuretic options for inpatient treatment include aldosterone antagonists (spironolactone) and loop diuretics. Aldosterone antagonists are preferred for people who can take oral medications and are not in need of an urgent volume reduction. Loop diuretics can be added as additional therapy.

If a rapid reduction of volume is required, paracentesis is the preferred option. This procedure requires the insertion of a plastic tube into the peritoneal cavity. Human albumin solution is usually given to prevent complications from the rapid volume reduction. In addition to being more rapid than diuretics, 4–5 liters of paracentesis is more successful in comparison to diuretic therapy.

If complications cannot be controlled or when the liver ceases functioning, liver transplantation is necessary. Survival from liver transplantation has been improving over the 1990s, and the five-year survival rate is now around 80%. The survival rate depends largely on the severity of disease and other medical risk factors in the recipient. In the United States, the MELD score is used to prioritize patients for transplantation. Transplantation necessitates the use of immune suppressants (ciclosporin or tacrolimus).

Individuals heterozygous for the Hb Lepore request no particular treatment. There is no anemia or, if there is, it is very mild.

Overall, hemoglobin C disease is one of the more benign hemoglobinopathies. Mild-to-moderate reduction in RBC lifespan may accompany from mild hemolytic anemia. Individuals with hemoglobin C disease have sporadic episodes of musculoskeletal (joint) pain. People with hemoglobin C disease can expect to lead a normal life.

There is currently minimal therapeutic intervention available for BENTA disease. Patients are closely monitored for infections and for signs of monoclonal or oligoclonal B cell expansion that could indicate B cell malignancy. Splenectomy is unlikely to reduce B cell burden; peripheral blood B cell counts rose significantly in three patients who underwent the procedure. It remains to be determined whether immunosuppressive drugs, including B cell-depleting drugs such as rituximab, could be effective for treating BENTA disease.

Hepatosplenomegaly (commonly abbreviated HSM) is the simultaneous enlargement of both the liver (hepatomegaly) and the spleen (splenomegaly). Hepatosplenomegaly can occur as the result of acute viral hepatitis, infectious mononucleosis, and histoplasmosis or it can be the sign of a serious and life-threatening lysosomal storage disease. Systemic venous hypertension can also increase the risk for developing hepatosplenomegaly, which may be seen in those patients with right-sided heart failure.