While a person may have certain signs and symptoms of polycythemia vera (PV), laboratory tests are needed to confirm the diagnosis. Generally, a doctor will consider other conditions first.

Sometimes a condition called “secondary polycythemia” is causing the increase in red blood cells but, unlike PV, it does not begin in the bone marrow and is not a cancer. High red blood cell counts caused by secondary polycythemia are a reaction to another problem such as: 

• High altitude
• Disease that leads to low oxygenation of the blood
• Kidney or liver tumor that secretes the hormone erythropoietin
• Inherited disease

Secondary polycythemia is managed primarily by treating the underlying condition causing the disorder. A patient with secondary polycythemia should have a return to normal red blood cell counts once the primary problem is successfully treated.

Medical History and Physical Examination

Evaluation of an individual with suspected PV should start with a detailed medical history and a physical examination by a hematologist-oncologist

The medical history should include information about the patient’s:

• Cardiovascular risk factors
• Past illnesses
• Injuries
• Treatments
• Medications
• A history of the formation or presence of a blood clot inside a blood vessel (thrombosis) or loss of blood from damaged blood vessels (hemorrhagic events)
• History of blood relatives—some illnesses run in families
• Current symptoms

After the medical history, the doctor will conduct a physical examination. During the physical examination, the doctor may:

• Listen to the patient's heart and lungs
• Examine the patient's body for signs of disease
• Check different organs of the body

Blood Tests

Complete Blood Count

This test measures the number of red blood cells, white blood cells and platelets in a sample of blood. It also measures the amount of the iron-rich protein that carries oxygen in red blood cells and the percent of whole blood made up of red blood cells (the hematocrit). People with PV have high red blood cell counts. They also often have:

• Increased white blood cells and platelets
• Increased hemoglobin levels
• Increased hematocrit levels

Red Cell Mast Test

This procedure is used to measure the volume (amount) of red blood cells in relation to the volume of plasma (fluid) in whole blood. In patients with PV, there may be an absolute increase in red blood cell mass. This test is infrequently performed in the United States due to high cost, difficulty obtaining the appropriate test materials, and the advent of new blood tests such as mutational testing.

Peripheral Blood Smear

A procedure in which a blood sample is viewed under a microscope. A pathologist examines the sample to see if there are any unusual changes in the size, shape and appearance of various blood cells. The test also checks for the presence of immature (blast) cells in the blood. 

Comprehensive Metabolic Panel

These tests measure the levels of substances released into the blood by organs and tissues. These include electrolyes, fats, proteins, glucose (sugar) and enzymes. Blood chemistry tests provide important information about how well a person’s kidneys, liver and other organs are working. For patients suspected of having PV, it is important to test the serum erythropoietin level. Erythropoietin is a hormone naturally produced by the kidneys to stimulate the production of new red blood cells. Individuals with PV usually have very low levels of erythropoietin. 

Bone Marrow Tests

Your doctor may examine your bone marrow even though the test isn't needed to diagnose PV.

Bone marrow testing involves two steps usually performed at the same time in a doctor's office or a hospital:

• A bone marrow aspiration to remove a liquid marrow sample
• A bone marrow biopsy to remove a small amount of bone filled with marrow

In PV, the bone marrow shows above-normal numbers of blood cells and an abnormal number of the platelet-forming cells called “megakaryocytes” in the bone marrow. The pathologist also examines the chromosomes of the bone marrow cells to rule out other blood diseases. 

Molecular Testing

Molecular genetic tests are very sensitive tests that look for specific gene mutations. If PV is suspected, molecular testing for the JAK2 mutation should be performed. The JAK2 V617F mutation is found in more than 90 percent of PV patients.

The U.S. Food and Drug Administration (FDA) has approved a test called ipsogen JAK2 RGQ PCR Kit to detect mutations affecting the Janus Tyrosine Kinase 2 (JAK2) gene. This test is intended to help doctors evaluate patients for suspected PV.

For more information about bone marrow tests and other lab tests, please see the free LLS publication Understanding Lab and Imaging Tests.

Criteria for Diagnosing Polycythemia Vera

In 2016, the World Health Organization published new criteria for diagnosing PV. The diagnosis of PV requires the presence of

• Major Criteria 1, 2, and 3 (listed below) or
• Major Criteria 1 and 2 and the minor criterion(listed below) 

Major Criteria 1.  Very high red blood cell count, usually identified by either A, B, or C below:

• A. Hemoglobin level
  • Elevated levels of hemoglobin
    • Hemoglobin levels greater than 16.5 g/dL in men
    • Hemoglobin levels greater than 16.0 g/dL in women
• B. Hematocrit level
  • Elevated levels of hematocrit
    • Hematocrit greater than 49 percent in men
    • Hematocrit greater than 48 percent in women
• C. Red cell mass
  • Increased red cell mass

Major Criteria 2. Bone marrow biopsy (A or B below) showing:

• A. An abnormal excess of blood cells in the bone marrow (called "hyercellularity") with an elevation of red blood cells, white blood cells and platelets (called "panmyelosis")
• B. Proliferation of mature megakaryocytes that vary in size and shape

Major Criteria 3. Presence of the JAK2V617F or JAK2 exon 12 gene mutation

Minor Criterion: Very low levels of erythropoietin

Related Links

• Download or order The Leukemia & Lymphoma Society’s free booklet, Myeloproliferative Neoplasms.
• Blood Tests
• Understanding Blood Counts
• Bone Marrow Tests