Common Blood Work Drawn In Myeloproliferative Neoplasms

Prior to being diagnosed with a myeloproliferative neoplasm, you may only rarely need blood work, such as once a year with your annual physical exam. Now, you might wonder—what is all this blood work? What is my doctor looking for? All the types of blood work that could be possibly ordered is more than we can review here, but let's look at the common ones.

Complete Blood Count (CBC)

A complete blood count (CBC) is one of the most common types of lab work used to monitor blood disorders. The CBC reviews your blood cells, which include white blood cells, red blood cells, and platelets. This test, which is often the first clue to what is causing your symptoms, is part of a regular diagnostic work-up and may be repeated frequently if you are undergoing treatment.

White blood cells (WBCs): White blood cells are a part of your immune system and help fight infections. There are five types of WBCs: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. The number of WBCs in your blood is usually the first number reported on the CBC. Part of the CBC, called the differential, or diff, looks at what percentage of each type of WBC is present.

In polycythemia vera (PV) or essential thrombocythemia (ET), your WBC count might be slightly elevated (leukocytosis). In primary myelofibrosis (PMF), some people will have an elevated WBC count, some a normal count, and others a low count (leukopenia).

Red blood cells (RBC): The red blood cells carry oxygen from the lungs to the organs. There are several ways to look at red blood cells on the CBC. First, the RBC count is the number of red blood cells in circulation. Hemoglobin is the protein found in the RBCs that carries oxygen. Hematocrit represents how much of the blood is made up of RBCs (as compared to WBCs and platelets).

In conditions that cause increased numbers of RBCs, like PV, the hemoglobin and hematocrit are elevated. The hematocrit is often used to monitor the effectiveness of treatment in PV. Medications and phlebotomy (physical removal of blood) are adjusted based on the desired hematocrit range (typically less than 45 percent in men and less than 42 percent in women).

In PMF, your hemoglobin level is part of the formula used to determine your prognostic score. This may change over the course of your illness. A hemoglobin level of less than 10 grams per deciliter (g/dL) at baseline counts as two points in the prognostic score (more points equal higher-risk disease). It can also be used to determine if you need a blood transfusion.

Blood transfusions are typically given when hemoglobin drops below 8 grams per deciliter, or if you are symptomatic (fatigue, dizziness, elevated heart rate). Requiring transfusions adds an additional point in the prognostic score.

Platelet count: A platelet count is also included in the CBC. Similar to hematocrit in PV, in people with ET requiring treatment, the platelet count is used to adjust treatments based on the desired platelet count. In PMF, a platelet count of fewer than 100,000 cells per microliter adds one point to your prognostic score.

Blood Smear

ET and PV can evolve into myelofibrosis and leukemia. The early signs of this change may be noted on the CBC, particularly a significant drop in the hemoglobin and platelet count. The red blood cells and platelets become abnormally shaped in myelofibrosis, which can be seen on a blood smear (a microscope slide of blood cells).

Von Willebrand Panel

People with ET are at risk of developing acquired von Willebrand disease, a bleeding disorder. This risk goes up as the platelet count goes up (more than one million platelets per microliter). If you have ET and bleeding, a von Willebrand panel may be taken to determine if this is the cause. Treatment focuses on reducing the platelet count.

A Word From Verywell

When you are getting frequent blood work, it can be difficult if you don't understand the reason for these tests. Discuss your concerns with your physician so that you can both be on the same page. Most likely, your doctor is ordering blood work to keep tabs on ongoing treatment and keep you in good health.