Common Blood Work Drawn In Myeloproliferative Neoplasms

Prior to being diagnosed with a myeloproliferative neoplasm, you may only rarely need blood work. Perhaps you have had blood drawn once a year with your annual physical exam. Now, though, you may wonder—what is all this blood work? What is my doctor looking for?

This type of abnormal growth, or neoplasm, is a disorder that may cause blood-related disease. In some cases, it may lead to leukemia. That's why blood tests are key to finding changes in these cells.

This article seeks to answer your questions about the most common types of blood work the doctor orders in these cases. It looks at three tests, and what they tell you and your doctor about the disease.

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 looks at all your blood cells, which include white blood cells, red blood cells, and platelets. This test, which may offer the first clues about what is causing your symptoms, is fairly routine as part of your diagnosis. It 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. In primary myelofibrosis (PMF), some people will have an elevated WBC count, some a normal count, and others a low count.

Red blood cells (RBC): The body's red blood cells carry oxygen from the lungs to the organs. There are a few ways to look at red blood cells on the CBC.

First, the RBC count is the total number of red blood cells circulating in the blood at the time. Hemoglobin is the protein found in the RBCs that carries oxygen. Hematocrit represents how much of the blood is made up of RBCs as a part of the overall blood plasma.

In conditions that cause the number of RBCs to rise, like PV, the hemoglobin and hematocrit numbers are up. The hematocrit is often used to check on how treatment for PV is working. Medications and phlebotomy (physical removal of blood) are adjusted based on the desired hematocrit range. This is typically less than 45% in men and less than 42% in women.

In PMF, your hemoglobin level is part of the math formula used to set 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 one point in the total score (more points equal higher-risk disease). It can also be used to see if you need a blood transfusion.

Blood transfusions are typically given when hemoglobin drops below 8 grams per deciliter. They also may be needed if you have symptoms like fatigue, dizziness, or a rapid heart rate. The anemia, or low level of RBCs, may add additional points to the prognostic score, though not necessarily the transfusion itself. Two points are added for severe anemia, and one for moderate anemia.

Platelet count: A platelet count also is part of the CBC. In people with ET that requires care, the platelet count serves as a treatment guide based on the desired platelet count. In PMF, a low platelet count also will add points to the 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, especially if there is a big drop in the hemoglobin and platelet count. The red blood cells and platelets become abnormally shaped in myelofibrosis. They can be seen on a slide of blood cells under a microscope, called the blood smear test.

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 done to see if this is the cause. Treatment focuses on reducing the platelet count.

Summary

The three blood tests discussed here are among the most common for people who have, or may have, a serious blood disorder. They are not the only ones doctors use to find and treat these conditions.

More blood work often is needed after the initial test because doctors want to continue to check the level of RBCs and other cells in the blood. It's a measure of how well treatment is working.

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.