Polycythemia vera (PV) may not cause signs or symptoms for years. The disease often is found during routine blood tests done for other reasons. If the results of your blood tests aren't normal, your doctor may want to do more tests.
Your doctor will diagnose PV based on your signs and symptoms, your age and overall health, your medical history, a physical exam, and test results.
During the physical exam, your doctor will look for signs of PV. He or she will check for an enlarged spleen, red skin on your face, and bleeding from your gums.
If your doctor confirms that you have polycythemia, the next step is to find out whether you have primary polycythemia (polycythemia vera) or secondary polycythemia.
Your medical history and physical exam may confirm which type of polycythemia you have. If not, you may have tests that check the level of the hormone erythropoietin (EPO) in your blood.
People who have PV have very low levels of EPO. People who have secondary polycythemia usually have normal or high levels of EPO.
If your primary care doctor thinks you have PV, he or she may refer you to a hematologist. A hematologist is a doctor who specializes in diagnosing and treating blood diseases and conditions.
You may have blood tests to diagnose PV. These tests include a complete blood count (CBC) and other tests, if necessary.
Complete Blood Count
Often, the first test used to diagnose PV is a CBC. The CBC measures many parts of your blood.
This test checks your hemoglobin (HEE-muh-glow-bin) and hematocrit (hee-MAT-oh-crit) levels. Hemoglobin is an iron-rich protein that helps red blood cells carry oxygen from the lungs to the rest of the body. Hematocrit is a measure of how much space red blood cells take up in your blood. A high level of hemoglobin or hematocrit may be a sign of PV.
The CBC also checks the number of red blood cells, white blood cells, and platelets in your blood. Abnormal results may be a sign of PV, a blood disorder, an infection, or another condition.
In addition to high red blood cell counts, people who have PV also may have high white blood cell and/or platelet counts.
Other Blood Tests
Blood smear. For this test, a small sample of blood is drawn from a vein, usually in your arm. The blood sample is examined under a microscope.
A blood smear can show whether you have a higher than normal number of red blood cells. The test also can show abnormal blood cells that are linked to myelofibrosis and other conditions related to PV.
Erythropoietin level. This blood test measures the level of EPO in your blood. EPO is a hormone that prompts your bone marrow to make new blood cells. People who have PV have very low levels of EPO. People who have secondary polycythemia usually have normal or high levels of EPO.
Bone Marrow Tests
Bone marrow tests can show whether your bone marrow is healthy. These tests also show whether your bone marrow is making normal amounts of blood cells.
The two bone marrow tests are aspiration (as-pi-RA-shun) and biopsy. For aspiration, your doctor removes a small amount of fluid bone marrow through a needle. For a biopsy, your doctor removes a small amount of bone marrow tissue through a larger needle. The samples are then examined under a microscope.
If the tests show that your bone marrow is making too many blood cells, it may be a sign that you have PV.