context: It's a blood cancer that begins in the marrow of your bones, the soft center where new blood cells grow. If you have polycythemia vera, your marrow makes too many red blood cells, which causes your blood to get too thick. That can make you more likely to have clots, a stroke, or a heart attack. This disease gets worse very slowly, usually over many years. Although it can be life-threatening if you don't get treatment, most people have a good chance of living a long life when they get the right care. If you have polycythemia vera, you'd usually find out about it when you're 60 or older. But it can happen at any age. It's more common among men than women. You might have warning signs like dizziness or feeling tired and weak, but lots of things can cause those symptoms. If you have polycythemia vera, the first sign may be when a routine blood test shows that you have a high number of blood cells. The treatment you get depends on your age and your situation. If you don't have a lot of symptoms, your doctor may just want to check you every now and then without treatment. It's natural to worry when you find out you have cancer. But remember, everyone is different and all cancers aren't the same. With the support of your doctor, family, friends, and other people who have polycythemia vera, you'll be in the best position to manage it. You don't "catch" polycythemia vera like you do a cold or the flu. It's something you get because you have a gene (either JAK2 or TET2) that doesn't work right. These genes are supposed to make sure your bone marrow doesn't make too many blood cells. Your bone marrow makes three types of blood cells: Red White Platelets Red blood cells carry oxygen, white fight infections, and platelets clot your blood to stop bleeding. Most people with polycythemia vera have too many red blood cells. But the disease can also cause you to have too many white blood cells and platelets. Most likely, the problem in your JAK2 or TET2 gene happened over the course of your life. It's rare, but parents can pass these broken genes to children. At first, you may not notice any problems. When you start having symptoms, they can include: Headaches Double vision Dark or blind spots in your vision that come and go Itching all over your body, especially after you've been in warm or hot water Sweating, especially at night A red face that looks like sunburn or blushing Weakness Dizziness Weight loss Shortness of breath Tingling or burning in your hands or feet Painful swelling of a joint You may also feel pressure or fullness below your ribs on your left side. Those symptoms come from an enlarged spleen, which can happen. The spleen is an organ that helps filter your blood. Without treatment, the extra red blood cells in your veins can cause clots that slow your blood flow. This makes you more likely to have a stroke or heart attack. It can also cause pain called angina in your chest. If your doctor thinks you might have polycythemia vera, you'll get a physical exam, including a check of your spleen. They'll also see if your face is unusually red. Your doctor may ask you questions like: Do you get a lot of headaches? Have you lost weight lately? Do you sometimes feel dizzy or weak? Have you had shortness of breath? Do you sweat a lot at night? You may get some blood tests, too. These include: Complete blood count ( CBC). Your doctor takes a sample of your blood and sends it to a lab, where a machine counts the number of red blood cells, white blood cells, and platelets you have. An unusually high number of any of these could be a sign of polycythemia vera. Blood smear. In this test, your doctor will look at a sample of your blood through a microscope. It's a way to check for other diseases that are sometimes linked to polycythemia vera. EPO level. This test measures how much of the hormone EPO you have in your blood. EPO tells your bone marrow to make blood cells. People who have polycythemia vera have very low amounts of it. You may also need to get a bone marrow biopsy. The results can show your doctor if your bone marrow makes too many blood cells. For this test, your doctor will take samples, usually from the back of your hip bone. It's an outpatient procedure, which means you don't have to stay overnight in a hospital. You can get it done in a clinic, a hospital, or your doctor's office. You lie down on a table and get a shot that will numb the area. Then your doctor uses a needle to take out a small amount of bone marrow. Before your appointment, it's a good idea to make a list of things to ask your doctor, such as: Which treatment do you recommend? What are the side effects? How can I prevent complications? Since I have polycythemia vera, am I more likely to have a stroke or heart attack? How can I ease my symptoms? Polycythemia vera is different for each person who has it. If you don't have many symptoms, you might not need treatment right away. Your doctor will keep a close watch on you. If you do need treatment, its goal is to lower the amount of red blood cells your body makes and prevent blood clots and other complications. Your options include: Phlebotomy. This is often the first treatment people with polycythemia vera get. Your doctor removes blood from your vein. It's a lot like donating blood. The goal is to lower your number of blood cells. After it's done, your blood will be thinner and it'll flow more easily. You'll usually feel better, too. Some symptoms will ease, like headaches or dizziness. Your doctor will decide how often you need phlebotomy. For some people, it's the only treatment they need for many years. Low-dose aspirin. This keeps platelets from sticking together. That makes you less likely to get blood clots, which in turn makes heart attacks or strokes less likely. Most people with polycythemia vera take low-dose aspirin. Medicine to lower blood cells. If you need more than phlebotomy and aspirin, your doctor may prescribe hydroxyurea ( Droxia, Hydrea), a pill that lowers your red blood count and eases symptoms. Another drug, interferon alfa ( Intron A), helps the immune system cut back on making blood cells. The drug ruxolitinib ( Jakafi) is approved for use in people who aren't helped by hydroxyurea or can't handle its side effects. If you have itching that doesn't go away, your doctor may prescribe antihistamines. There are a lot of ways you can keep yourself comfortable and as healthy as possible: Don't smoke or chew tobacco. Tobacco makes blood vessels narrow, which can make blood clots more likely. Get some light exercise, such as walking, to help your circulation and keep your heart healthy. Do leg and ankle exercises to stop clots from forming in the veins of your legs. Your doctor or a physical therapist can show you how. Bathe or shower in cool water if warm water makes you itch. Keep your skin moist with lotion, and try not to scratch. Although there's no cure, the right treatment can help you manage this disease for many years. Remember that everyone's case is different. With good care, you can still have an active lifestyle. It's rare, but your condition could lead to acute leukemia or myelofibrosis, which are also blood diseases but are more serious than polycythemia vera. Acute leukemia is a blood cancer that gets worse quickly. Myelofibrosis is a condition in which your bone marrow gets filled with scar tissue. Talk to your friends and family about how to keep a positive attitude. You may also want to join a support group for people with your condition. The MPN Research Foundation has more information about polycythemia vera. It can also help you find support groups.