An Overview of Blood Disorders

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Blood disorders involve problems in your blood or bone marrow, the fatty area inside your bones that produces new red blood cells, white blood cells, and platelets. When something goes wrong with any of these cell types or with the clotting factors in the plasma (the liquid part of the blood), you may be diagnosed with a blood disorder. The most common types are anemia, bleeding disorders such as hemophilia, and blood clots.

In general, when physicians refer to something as a blood disorder, they are implying that the condition is not cancerous (i.e., leukemia or lymphoma).

Laboratory technician holding test tubes containing blood samples

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Types and Causes

Blood disorders can be inherited or acquired. Sometimes you develop a blood disorder due to an infection, toxic exposure, drug side effect, or lack of certain nutrients in your diet (such as iron, vitamin K, or vitamin B12).

Blood disorders are defined by changes in any of the parts of your blood:

  • White blood cells, which help fight infections: They include neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
  • Red blood cells, which carry oxygen to tissues
  • Platelets, which help stop bleeding
  • Plasma, which carries various components including procoagulant factors (that help stop bleeding) and anticoagulant factors (that prevent clot formation)

Following are common blood disorders:

  • Neutropenia is a decreased number of neutrophils, a type of white blood cell. The neutrophils are an important part of your immune system that help fight off bacterial infections. The most common cause of neutropenia is chemotherapy given to treat cancer. Other causes include autoimmune neutropenia, Shwachman-Diamond syndrome, and cyclic neutropenia.
  • Anemia results from a decreased number of red blood cells or hemoglobin—the protein that carries oxygen. Anemia can result from iron deficiency, sickle cell disease, or thalassemia, as well as a number of other conditions and diseases.
  • Polycythemia vera (PV) is a condition in which your bone marrow makes an excessive number of red blood cells. This increase can elevate your risk of clot formation.
  • Immune thrombocytopenic purpura (ITP) is a condition in which your platelets are marked as “foreign” and are, therefore, destroyed. This can lead to very low platelet counts and bleeding.
  • Thrombocytosis refers to an increased number of platelets. Fortunately, most of the time, elevated platelet counts are caused by something else (reactive thrombocytosis) and will get better when the underlying condition improves. More concerning, however, are blood conditions like essential thrombocythemia (ET), where your bone marrow makes an extremely high number of platelets, increasing the risk of developing a blood clot, and sometimes bleeding.
  • Hemophilia is an inherited condition that results in decreased amounts of procoagulant factors (specifically, 8, 9, and 11). This results in easy bleeding. People with hemophilia are sometimes referred to as “free bleeders.”
  • Blood clots (thrombosis) can occur anywhere in the body. In the brain, it is called a stroke; in the heart, it is called a heart attack (or myocardial infarction). Deep vein thrombosis (DVT) commonly refers to blood clots in the arms or legs.

Some blood disorders live in a space between benign and malignant (cancerous)—sometimes referred to as premalignant—and may evolve into cancer. Leukemia is generally not included in the broader term of blood disorders as it is a cancer of the blood/bone marrow.


Symptoms of blood disorders vary widely depending on which blood component is affected. Some blood disorders cause few symptoms, while others are responsible for more.

For example:

  • Anemia (low red blood cells) can cause fatigue, shortness of breath, or increased heart rate.
  • Thrombocytopenia (low platelets) can cause increased bruising or bleeding from the mouth or nose.
  • Hemophilia (poor clotting) can also cause increased bleeding but is known to specifically target muscles and joints without significant injury.
  • Blood clots (inappropriate clotting) in the arms or legs may cause swelling and pain.


Blood disorders are predominantly seen by hematologists—physicians who specialize in the diagnosis and treatment of problems in your blood and/or bone marrow.

Your physician will examine you and your symptoms to determine the most likely diagnosis. Most of the time blood work is needed. Sometimes blood disorders are found on lab work drawn for other reasons like an annual physical exam.

The most commonly used test to diagnose blood disorders is the complete blood count (CBC). The CBC looks at the three types of blood cells and determines if any are increased or decreased or if more than one blood cell is affected. A blood smear may also be included with the CBC, with a microscopic examination to provide additional helpful information.

For bleeding or clotting problems, your physician will likely order coagulation blood tests, which include the prothrombin time (PT) and the partial thromboplastin time (PTT). If the PT or PTT is prolonged (indicating that you are more likely to bleed than other people), further evaluation is needed. Your physician may order levels of individual coagulation factors or assess the function of your platelets.

Blood clots are a little different. To diagnose them, your physician will need to image the concerning area. In the arms or legs, an ultrasound is used to assess for possible clots. In the lungs or brain, computerized tomography (CT) or magnetic resonance imaging (MRI) scans are commonly used.

A bone marrow biopsy may be needed in some cases to help make a diagnosis. This is usually done by aspirating marrow from the hip.


Treatment is determined by your specific diagnosis. Some chronic blood disorders have no specific treatment but may require treatment during acute events. For example:

  • Anemia caused by iron deficiency will be treated with iron supplementation. Beta thalassemia major, an inherited form of anemia, is treated with monthly blood transfusions.
  • Hemophilia can be treated with coagulation factor replacement products that can be used to treat individual bleeds or, when given on a regular basis, prevent bleeds (prophylaxis).
  • Polycythemia vera is treated by phlebotomy—drawing a pint of blood intermittently to keep the number of red cells from dropping below the dangerous level.
  • Blood clots may be treated with anticoagulant therapy (blood thinners). Some cases may require catheter-directed thrombolysis to dissolve the blockage.
  • Thrombocythemia may be treated with aspirin or might require medications such as hydroxyurea, interferon alfa, or anagrelide (rarely used).
  • Immune thrombocytopenia might be treated with corticosteroids such as prednisone or medications that raise the platelet count. Removing the spleen is another treatment performed when needed.

It is important to discuss with your physician what the best treatment is for you and your diagnosis.

A Word From Verywell

Learning you or a loved one possibly has a blood disorder can be alarming. Sometimes this stress is increased when you are referred to a cancer center to see a specialist. This doesn’t necessarily mean your physician thinks you have cancer. Most hematologists are also trained in oncology (diagnosis and treatment of cancer) and work in clinics with oncologists. Hopefully, having a better understanding of what blood disorders are will alleviate some of your concerns.

12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. American Society of Hematology. Anemia.

  3. James RM, Kinsey SE. The investigation and management of chronic neutropenia in childrenArch Dis Child. 91(10):852–858. doi:10.1136/adc.2006.094706

  4. Cleveland Clinic. Anemia.

  5. Kroll MH, Michaelis LC, Verstovsek S. Mechanisms of thrombogenesis in polycythemia vera. Blood Rev. 29(4):215-21. doi:10.1016/j.blre.2014.12.002

  6. Olsson M, Hagnerud S, Hedelius DUR, et al. Hematologic Diseases: Autoimmune Hemolytic Anemia and Immune Thrombocytopenic Purpura. In: Madame Curie Bioscience Database.

  7. NIH U.S. National Library of Medicine Genetics Home Reference. Essential thrombocythemia.

  8. Cleveland Clinic. Benign Hematology.

  9. George-gay B, Parker K. Understanding the complete blood count with differential. J Perianesth Nurs. 18(2):96-114. doi:10.1053/jpan.2003.50013

  10. National Organization of Rare Disorders. Beta Thalassemia.

  11. Centers for Disease Control and Prevention. Hemophilia.

  12. Khan AM, Mydra H, Nevarez A. Clinical Practice Updates in the Management of Immune ThrombocytopeniaP T. 42(12):756–763.

Additional Reading
  • Kaushansky K, Lichtman MA, Prchal J, Levi MM, Press O, Burns L, Caligiuri M. Williams Hematology (9th ed.) USA. McGraw-Hill Education.