The diagnosis of polycythemia vera may be suspected after a history and physical exam. A blood test called a complete blood count (CBC) is the first step in making the diagnosis. This test counts the number of each of the kinds of blood cells. A person with polycythemia vera has an elevated red blood cell count, and usually has elevated white blood cell and platelet counts as well. Other blood tests, such as a vitamin B12 level or an erythropoietin level, may also be done.
Often, a procedure called a bone marrow biopsy is done to help confirm the diagnosis. This involves inserting a special needle through the skin of the upper buttock area and into the pelvic bone. The needle is used to take a sample of bone marrow, the soft material found inside certain bones where blood cells are made. The sample of marrow can be sent to the lab for examination and special testing.