Anyone who has a myeloproliferative neoplasm (MPN) will have to undergo a great deal of blood tests. The complete blood count (CBC) is one of the most common. The test measures both red blood cell count and white blood cell count in a blood sample, but there’s more to it than that. Here’s a breakdown of what doctors are looking for and why.
Complete blood counts give both the number of cells in your blood currently and what types of cells they are. Three different types of cells make up blood: red blood cells, white blood cells, and platelets. Red cells are also referred to as erythrocytes. Their primary function is to carry oxygen from the heart and lungs to different parts of the body. White cells are also known as leukocytes. They work as a first-line defense for the immune system, fighting bacteria and viruses that may enter the blood. Platelets are round cells that gather at places of injury and help blood clot.
Two other functions of blood are usually tested in a CBC: hematocrit and hemoglobin. Hematocrit levels measure how much of your blood is currently made up of red cells. Hemoglobin measures the level of red cells in your blood.
Red blood cell levels, white blood cell levels, and platelet levels are typically given in units per microliter of blood. “Normal” blood counts vary by individual. However, there are general ranges for men, women, and children. The normal range of red blood cells per microliter is usually 4.7 million to 6.1 million for men, 4.2 million to 5.4 million for women, and 4 million to 5.5 million for children. The normal range of white blood cells per microliter is usually 5,000 to 10,000 for men, 4,500 to 11,000 for women, and 5,000 to 10,000 for children.
Normal hematocrit levels are 42 percent to 52 percent of the total blood count for men, 37 percent to 47 percent for women, and 32 percent to 44 percent for children. Platelet counts, regardless of age or gender, are considered normal at 150,000 to 400,000 per microliter.
White blood cells are also counted in a white blood cell differential. There are five different types of white blood cells: neutrophils, eosinophils, lymphocytes, monocytes, and basophils. In a normal blood count, neutrophils make up around 55 percent to 70 percent of all white blood cells. Lymphocytes make up anywhere from 20 percent to 40 percent, monocytes 2 percent to 8 percent, and basophils and eosinophils make up the rest.
Watch MPN expert Dr. Ruben Mesa discuss how you can interpret your blood results.
People living with MPNs won’t have normal blood counts. Depending on the type of MPN a person has been diagnosed with, the counts may be abnormal in several different areas. For those with essential thrombocythemia, platelet counts will be abnormally high (a condition called thrombocytosis). Those with polycythemia vera will have too many red blood cells (and possibly too many white blood cells and platelets). Those with primary myelofibrosis may have an abnormal count of immature blood cells (blast cells) along with too many white blood cells and often too few red blood cells and platelets. A person with chronic eosinophilic leukemia/hypereosinophilic syndrome will have a high white blood cell count, especially of eosinophils.
While it’s not considered an MPN by some researchers, chronic myeloid leukemia will have blood tests showing immature white blood cells, specifically myelocytes and metamyelocytes. The reason for this is the bone marrow environment. Inside the bone marrow, stem cells develop that will become mature blood cells. In an MPN, the bone marrow produces an abnormal amount of one or more types of cells.
Blood tests are crucial in managing MPNs because they dictate the amount of treatment needed at any given time. Proper monitoring and treatment can keep a person healthy throughout the rest of their life. Since there is a small possibility an MPN will progress to acute myeloid leukemia if not treated, it’s especially important to monitor your condition.
After reviewing your complete blood count results, your doctor may recommend a change in treatment. Treatments for myeloproliferative neoplasms depend upon the condition.
Treatment for essential thrombocythemia involves preventing blood clots and bleeding. Blood clots form more easily when platelet counts are high, and this can lead to heart attack or stroke. Low-dose aspirin is usually the first treatment. Aspirin contains a chemical that makes it harder for platelets to stick to each other. Occasionally, aspirin will cause excessive bleeding as a side effect. Because of this, any aspirin use needs to be carefully monitored by your doctor.
Polycythemia vera is treated in a similar way. The goal in this case is not to prevent platelets from sticking to each other, but to keep the blood’s hematocrit level below 45 percent. Low-dose aspirin is used as a first-line treatment, but phlebotomy (therapeutic blood drawing) is also used. After a blood draw, the number of red cells goes down and there is less chance of red blood cells gathering around blood vessels. If phlebotomy is given too frequently, it can result in anemia from removal of the red cells. This needs to be monitored by periodic blood testing.
Myelofibrosis is trickier to treat because there is no one universal treatment for it. Asymptomatic people with myelofibrosis may undergo no treatment at all. A person is considered asymptomatic when they are not anemic and do not have an enlarged spleen. Even an asymptomatic person needs to be monitored, because if symptoms start to progress, more serious conditions can result. If someone is experiencing symptoms, Jakafi (ruxolitinib) is a common treatment.
There is no standard treatment for chronic eosinophilic leukemia. It can be treated with corticosteroids to control symptoms. Immunotherapy or chemotherapy are also treatment options. In some instances the spleen may be removed. The spleen is responsible for making some white blood cells and its removal can decrease the overall white count. Treatment usually continues until the white cell count has gone down. However, this can also make someone more susceptible to infection.
All this blood testing is a delicate balancing act. Knowing your health is dependent upon blood count ranges can be hard to live with. Your doctor can help you with any medical questions you might have about your blood test results. Other members of myMPNteam can also support you and offer advice on how to deal with blood count tests and their effects.