An Overview of Blood Disorders

Blood disorders involve problems in our blood or bone marrow. After birth, our bone marrow (fatty area in the middle of our bones) is the primary source of new blood cells. Often, problems with the way our bone marrow produces blood cells results in blood disorders. Blood disorders can occur from any of the four parts of our blood:

  1. White blood cells—which help fight infections.
  2. Red blood cells—which carry oxygen to tissues.
  3. Platelets—which help stop bleeding.
  4. Plasma—which carries various components including procoagulant factors (that help stop bleeding) and anticoagulant factors (that prevent clot formation).

View an artery and red blood cells close-up.

Elevated white blood cell counts are called leukocytosis and low counts are called leukopenia. There are five types of white blood cells, all of which may be affected:

  1. Granulocytes (also called neutrophils or segmented neutrophils)
  2. Lymphocytes
  3. Monocytes
  4. Eosinophils
  5. Basophils

Many medical conditions fit under the broad diagnosis of blood disorder yet vary greatly. In general, when physicians refer to something as a blood disorder, they are implying that it is not cancerous (benign).

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

Common Types

  • Neutropenia is a decreased number of neutrophils, a type of white blood cell. The neutrophils are an important part of your immune system that fights off bacterial infections. There are numerous causes including 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.
  • 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) which 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 numbers of platelets which increase the risk of developing a blood clot.
  • Hemophilia is an inherited condition which results in decreased amounts of procoagulant factors (8, 9, and 11). This results in easy bleeding. People with hemophilia are sometimes referred to as “free bleeders”.
  • Blood clots (also called 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.


Symptoms of blood disorders vary as widely as the diagnoses. Some blood disorders cause few symptoms, while others are responsible for more. For example:

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


Your physician will examine you and your symptoms to determine the most likely diagnosis. This will identify the work-up needed to confirm the diagnosis. As you may have guessed, 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 either one of the blood cells is increased or decreased or if more than one blood cell is affected. This information can lead to a diagnosis or inform whether further work-up is needed. A blood smear may be also be included with the CBC and allows your physician (or pathologist) to look at the blood cells under the microscope to provide additional helpful information.

If you have a lot of bleeding, your physician will likely look at a blood test commonly referred to as “coags”. “Coags” generally includes two tests that look at your coagulation system—the prothrombin time (PT) and the partial thromboplastin time (PTT). These tests provide general information on how well your blood clots. If the PT or PTT are prolonged (indicating that you are more likely to bleed than other people), further work-up will be performed. Your physician may order levels of the 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, CT (computerized tomography) or MRI (magnetic resonance imaging) scans are commonly used.


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).

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.

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Article Sources
  • Kaushansky K, Lichtman MA, Prchal J, Levi MM, Press O, Burns L, Caligiuri M. (2016). Williams Hematology (9th ed.) USA. McGraw-Hill Education.