context: Polycythemia vera ( PV) is a slow-growing blood cancer in which your body makes too many red blood cells. You may have it for years before you notice any symptoms. Most people find out they have PV because they had a blood test for some other reason. If your doctor thinks you have PV, you'll start with a physical exam. Then you may need: Blood tests A bone marrow test A genetic test You may not get all of these tests, but you're likely to get some of them. This helps you know for sure that you have PV and not a similar blood disease. Your doctor will probably send to you a hematologist -- a doctor who treats blood diseases. You may want to write down any questions you have so you remember them. For example, you could ask: What's the cause of my condition? What tests do I need? When will I find out about my results? How I can learn more about PV? You may also want to write some notes about how you're doing and what you've noticed. This can help you answer questions your doctor might ask, like: What symptoms are you having? How long have you had them? Do you have them some of the time or all of the time? How strong are your symptoms? Does anything make them better? Worse? At your exam, your doctor will check your body for signs of PV. She may: Check your gums for bleeding Look at your skin for redness Press on your belly to know if your spleen or liver is larger than normal Take your blood pressure to see if it's high Check your pulse Your physical exam is a starting point. It gives your doctor a better sense of what's happening with your body. Blood tests are common when checking for PV. Even if you've already had one, you may need another. Your doctor may order any of these tests: Complete blood count Blood smear Erythropoietin level Complete blood count: The complete blood count ( CBC) is often the test first that shows you might have PV. It measures: Hemoglobin. This is a protein that helps your red blood cells carry oxygen throughout your body. Hematocrit. To understand hematocrit, think of your blood as colored marbles in a jar of water. Red marbles are your red blood cells. Hematocrit is a number. It tells you how much room the red marbles take up in that jar -- or how much room your red blood cells take up in your blood. Number of blood cells. You have three kinds of blood cells: red, white, and platelets. The CBC counts how many of each you have. High numbers for hemoglobin, hematocrit, or blood cell count can all be signs of PV. The CBC takes only a few minutes. Your doctor puts a thin needle into your arm, usually near your elbow, and draws blood. You may have results in 1-2 days, but it can take longer. Blood smear: Like the CBC, a blood smear gives a blood cell count. It also shows the shape of your blood cells. This helps your doctor know if you have PV and how advanced it might be. The blood smear is a quick test. Your doctor may draw blood from your arm or by pricking your finger. You usually get the results in 1-2 days. Erythropoietin level: Erythropoietin ( EPO) is a hormone that tells your bone marrow to make new blood cells. A very low level can be another sign of PV. The EPO test is quick with a blood draw from your arm. You can get EPO test results in 2-3 days, but your lab may take longer. Bone marrow is the spongy center part of your bones that makes your blood cells. Your doctor may decide you need a bone marrow test. There are two kinds of bone marrow tests: Aspiration uses a liquid bone marrow sample Biopsy uses a solid bone marrow sample Both tests show if your bone marrow is making too many blood cells. You may get both tests done at the same time. This lasts 10-30 minutes. Your doctor first numbs an area around either your breastbone or your pelvic bone. If you feel anxious about the test, you can also get medicine to help keep you calm. Your doctor then uses a needle to take the bone marrow sample. You can get results in 3-4 days, but it may take longer. Most people with PV have a problem in a gene called JAK2. Your doctor can use a blood sample or a bone marrow sample from a biopsy to check your JAK2 gene. You can get results in 4-6 days, but your lab may take longer. If tests show that you have PV, your doctor can help you choose the best treatment for you and closely follow your health in the years to come to make sure you don't have complications. Most people with PV can live a normal life. With the right care, you can limit your symptoms and, in some cases, make them go away completely.