Diagnosing Myeloproliferative Disorders
NYU Langone doctors are experts at diagnosing myeloproliferative disorders, in which the bone marrow does not function normally and produces too many blood cells.
Depending on the type of myeloproliferative disorder, the affected blood cells may include red blood cells, which carry oxygen and other nutrients to the body’s tissues and organs; white blood cells, which help fight infection; and platelets, which aid in blood clotting.
Abnormalities in immature blood-forming cells, called stem cells, can also occur, causing them to grow too rapidly. The growth of these cells can damage and scar the bone marrow. High levels of abnormal stem cells can cause anemia, a condition in which there are too few healthy red blood cells, leading to weakness and fatigue.
People with myeloproliferative disorders do not always have symptoms. However, a routine blood test may reveal an unhealthy level of one or more of the blood cells that may be associated with one of these disorders.
Signs and Symptoms of Myeloproliferative Disorders
When people do experience symptoms, these are typically related to the type of blood cell levels that are increased. General symptoms of increased blood cell production in myeloproliferative disorders are fatigue, fevers, weight loss, bone pain, and night sweats. Abnormal blood cell levels may also cause infections.
Another sign of myeloproliferative disorders is the shift of blood cell production from the bone marrow to the spleen. As a result, the spleen may become enlarged and painful, a condition called splenomegaly. An enlarged spleen can put pressure on the stomach, causing a feeling of fullness.
Increased levels of blood cells can also block blood vessels in the liver, increasing blood pressure in the vein that connects the digestive system to the liver. This condition, called portal hypertension, can cause the liver to become enlarged and the abdomen to swell.
Other possible signs and symptoms depend on the type of myeloproliferative disorder a person has. For example, increased levels of platelets and red blood cell can thicken the blood, causing some people to develop blood clots. People with anemia may experience weakness and shortness of breath.
Risk Factors for Myeloproliferative Disorders
Risk factors for myeloproliferative disorders are largely unknown, but these conditions tend to be linked to certain gene mutations.
For example, normal versions of a gene called Janus kinase 2 (JAK2) produce an enzyme needed to turn blood cell production on and off. Mutations in this gene result in constant increased blood cell production.
Depending on which cells are stimulated by a JAK2 mutation, one of several types of myeloproliferative disorders can develop, including polycythemia vera, essential thrombocythemia, and primary myelofibrosis.
A mutation in the calreticulin (CALR) gene drives platelet production, typically resulting in essential thrombocythemia and primary myelofibrosis. Mutations in another gene, called MPL proto-oncogene, thrombopoietin receptor (MPL), can increase the risk of essential thrombocythemia or primary myelofibrosis.
Diagnosing Myeloproliferative Disorders
Your hematologist asks about your medical history, evaluates any signs and symptoms, and uses blood tests and gene mutation studies to diagnose myeloproliferative disorders.
A bone marrow biopsy may be performed if more information is needed.
A blood test checks the level, shape, and size of white cells, red cells, and platelets. The level of blood cells, as well as the presence of certain proteins, hormones, or other substances in the blood, can help doctors identify the type of myeloproliferative disorder.
NYU Langone hematopathologists—doctors who study diseases of the blood—also use sophisticated tests to look for gene mutations, which are associated with different types of myeloproliferative disorders.
Signs of polycythemia vera include increased levels of red blood cells and of hemoglobin, the protein in red blood cells that carries oxygen. A low level of erythropoietin, a hormone that stimulates the production of red blood cells, is also a sign. High levels of platelets and white blood cells may also be present. Polycythemia vera is often associated with a JAK2 gene mutation.
High platelet levels alone may signal essential thrombocythemia. A JAK2 gene mutation may also be present. Some people may have CALR or MPL gene mutations.
Low levels of red blood cells and unusual levels of white blood cells and platelets may be signs of primary myelofibrosis, in which scar tissue in the bone marrow leads to decreased blood cell production. Platelets may also appear large or malformed. JAK2, CALR, or MPL gene mutations are associated with this condition.
Bone Marrow Aspiration and Biopsy
If blood tests do not confirm gene mutations in the blood cells, doctors may recommend a bone marrow aspiration and biopsy to make a diagnosis.
During this procedure, in which a local anesthetic is used, your doctor uses a small needle to remove bone marrow fluid from the pelvic bone in the lower back. He or she then uses a larger needle to remove a small part of the pelvic bone. These cells are then sent to a laboratory for analysis by a hematopathologist, who performs sophisticated genetic testing.
You can go home the same day as the procedure.
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