Polycythemia vera diagnosis

Polycythemia vera (PV) is a rare, slow-growing type of blood cancer that causes your bone marrow to make too many blood cells. It primarily affects red blood cells, but you may also have higher-than-normal levels of certain white blood cells and platelets, which help your blood clot.

PV is part of a group of chronic blood cancers called myeloproliferative neoplasms. Because PV can cause signs and symptoms similar to those of other blood disorders and health conditions, obtaining an accurate PV diagnosis may require several steps.

Understanding the tests used to diagnose PV can help you know what to expect and prepare questions for your care team.

How is PV diagnosed?

Diagnosing PV is often a multistep process. Your doctor will usually start by asking about your symptoms, medical history, and lifestyle habits, and conduct a detailed physical examination to check your body for signs of disease. This step will be followed by blood tests to check the number of your blood cells and your hematocrit level, or the proportion of red blood cells in your blood.

If your initial test results suggest PV or another blood disorder, your doctor may order additional blood tests or a bone marrow biopsy, which examines the content of the spongy tissue inside bones where blood cells are made. These tests can provide more information about your blood cells and identify genetic changes that may help confirm a diagnosis.

Complete blood count and hematocrit testing

Because early PV symptoms can be mild or similar to those of other conditions, doctors sometimes first suspect the condition after routine blood tests show abnormal blood cell counts.

A complete blood count (CBC) measures the number of red blood cells, white blood cells, and platelets in your blood. It also provides important information about your red blood cells.

Two important measurements used when evaluating you for PV are:

• hematocrit: The percentage of your blood made up of red blood cells.
• hemoglobin: A protein in red blood cells that carries oxygen in your blood.

Elevated hemoglobin or hematocrit levels may indicate PV. Your doctor will consider these results along with other PV diagnostic criteria, such as genetic test results and, in some cases, a bone marrow examination showing abnormally high numbers of blood cells.

JAK2 mutation testing

Nearly all people with PV have a mutation in the JAK2 gene, making genetic testing one of the most important PV diagnostic tools. If your CBC results suggest PV, your doctor may order testing for a JAK2 mutation. 

JAK2 mutation testing for PV is usually performed using a blood sample. If you have elevated hemoglobin or hematocrit levels and genetic testing detects a JAK2 mutation, you will almost certainly be diagnosed with PV.

If initial testing does not identify a JAK2 mutation but your doctor still suspects PV, they may recommend additional or more sensitive testing.

Bone marrow biopsy

Your doctor may also recommend a bone marrow biopsy as part of the diagnostic process. During a bone marrow biopsy, a healthcare professional removes a small sample of bone marrow, usually from the back of your hip bone, for testing.

Your care team may use a bone marrow biopsy for PV to examine the number, types, and appearance of blood-forming cells in your bone marrow.  The test can also help identify scarring, called fibrosis, that may suggest PV has progressed to myelofibrosis.

If testing shows signs of disease progression, your care team can discuss what the results mean and whether changes to your treatment plan may be appropriate.

Erythropoietin testing

Another PV blood test your doctor may order is a serum erythropoietin (EPO) test. EPO is a hormone made by the kidneys in response to low oxygen levels that signals your bone marrow to make red blood cells.

People with PV typically have low EPO levels, and current PV diagnostic guidelines include EPO levels as one of the criteria that may support a diagnosis. If you have elevated hematocrit or hemoglobin levels and your bone marrow biopsy shows signs consistent with PV, having EPO levels below the normal reference range is enough to make a PV diagnosis.

Ruling out secondary polycythemia

Secondary polycythemia is a condition in which your body produces more red blood cells than it should, but rather than being caused by genetic mutations, it arises from another condition, medication, or environmental factor.

These conditions cause your body to produce too much EPO, so measuring your EPO level may also help your doctor distinguish PV from secondary polycythemia.

To help rule out secondary polycythemia, your doctor may also ask about your:

• lifestyle and environment: Living at a high altitude, smoking, or prolonged exposure to carbon monoxide may reduce oxygen levels in your blood and trigger EPO production, leading to excess red blood cell production.
• medical history: Conditions that cause low oxygen levels, such as lung disease or sleep apnea, may similarly lead to increased red blood cell production.
• medications: Certain medications, including synthetic EPO, testosterone, and some medications used to lower blood sugar, may also raise EPO levels and contribute to elevated red blood cell counts.

Your doctor may recommend tests to evaluate your kidney function or look for certain tumors or genetic mutations that can increase EPO production.

What diagnostic results can and cannot tell you

Getting a PV diagnosis can raise many questions and concerns. Learning what your test results mean and discussing them with your care team can help you better understand your condition and what comes next.

Your diagnostic results can help explain symptoms you may be experiencing, confirm whether you have PV, and guide treatment decisions. Treatments for PV continue to improve, and people with the condition may live for many years with ongoing care and monitoring.

However, a single diagnostic test cannot predict exactly how PV will affect you, or if or when the disease might progress. Instead, your care team will evaluate your overall test results, symptoms, age, and health history when discussing your outlook and treatment plan.

Questions to ask after a PV diagnosis

After receiving a PV diagnosis, you may have questions about your test results, symptoms, and treatment options.

Consider asking your care team:

• What can I do to help reduce my risk of blood clots?
• What symptoms should I watch for?
• What treatments do you recommend for me?
• Are there treatments that may help ease my PV symptoms?
• Are there clinical trials that may be a good fit for me?

Writing down your questions before an appointment may help you remember what you want to discuss. Your care team can explain your test results and help you understand the next steps in managing PV.

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Rare Cancer News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.