Evaluation of Blood Counts in Polycythemia Vera

By Editorial Team

3 min read

Last updated: February 2023

Polycythemia vera (PV) is an uncommon slow-growing blood cancer in which bone marrow produces excess red blood cells. You can have it for years without having any symptoms. It is often discovered in routine blood tests. There is no known cause for the disease. Even though it is reflective of a genetic mutation, it is not an inherited condition.¹

A type of myeloproliferative neoplasm blood cancer, polycythemia vera is characterized by a gene mutation that interferes with normal blood cell production.² The Janus kinase 2 (JAK2) mutation causes cells to grow faster than normal in bone marrow. The condition generally develops in people over age 60 but can arise earlier.^1-3

Symptoms of polycythemia vera

Symptoms include but are not limited to:^1-3

Itchiness, bleeding and bruising
Headache and dizziness
Numbness, tingling, weakness, and fatigue
Fevers, blurry vision
Fullness or bloating in your left upper abdomen symptomatic of an enlarged spleen

A diagnosis of polycythemia vera is made based on results from blood tests, genetic tests, and bone marrow analysis. Cells measured in the blood to diagnose PV include: the hematocrit, hemoglobin concentration, and red cell count. Elevated hemoglobin, hematocrit, or blood cell count can all be indicators.^1,2

Blood tests

Complete Blood Count (CBC) is a thorough cellular analysis of the blood. It measures numerous blood components including:²

Hemoglobin (Hgb), an iron-rich protein that helps red blood cells carry oxygen throughout the body. The normal range for hemoglobin is 13.5 to 17.5 grams per deciliter for men, and 12.0 to 15.5 grams per deciliter for women.
Hematocrit (Hct), the proportion of red blood cells in a volume of blood, expressed as a percentage or an increase in hemoglobin concentration in the blood. Normal hematocrit concentration ranges from 36 to 46 percent in women and 42 to 52 percent in men.
Number of Blood Cells is a count of each type of cell present in the blood.
Blood Smear looks at the number and shape of the red and white blood cells and platelets in the blood to see whether they appear normal.
Erythropoietin level (EPO) is a hormone produced by the kidneys to stimulate bone marrow to make red blood cells. The normal range for EPO can vary from 3.7 to 36 international units per liter (IU/L). Unusually low levels can be caused by polycythemia vera.
Bone Marrow Tests check the bone marrow for red blood cell production to see if they develop and function normally.
Aspiration is a technique used to withdraw a sample of the liquid portion of bone marrow.
Biopsy is the surgical removal of a sample of solid bone marrow material.
Gene Testing looks for the presence of the gene mutation, JAK2, associated with polycythemia vera.

In polycythemia vera, there are too many red blood cells, and sometimes there are also too many platelets or white blood cells. The effect of this surplus of red blood cells can make the blood thicker, more viscous.² This can cause complications that develop into more serious blood diseases and may even become life-threatening When blood doesn’t flow smoothly; it can lead to the formation of clots. Clots can lead to stroke, heart attack, deep vein thrombosis, or pulmonary embolism.^1-3

Nearly 30% of people experience blood clots before they have a PV diagnosis. In the 10 years after diagnosis, 40 to 60 percent of people with untreated PV could develop blood clots. Other complications can include splenomegaly, which is when the spleen becomes enlarged from working overtime to help eliminate waste and fight infection.^1,3 Although rare, when left untreated, PV can develop into other blood disorders including myelofibrosis, myelodysplastic syndrome, and leukemia.

Treatments to address blood conditions

While PV has no cure, there are treatments that can diminish symptoms and lessen the risk of developing complications. Treatments are aimed at reducing both the amount of blood cells and overall volume.^1,2 These include: