Hello, Polycythemia vera is a rare condition usually affecting men in their 60s.  The condition is rarely seen in people under age 40. Although the cause of polycythemia vera is unknown, a number of factors are involved that appear to lead to secondary polycythemia. A high content of red blood cells builds up in response to low oxygen concentration in the air. The bone marrow can also be overstimulated by testosterone replacement therapy. Living for long periods at high altitudes where there's less oxygen may lead to polycythemia. It also may occur in people with chronic lung conditions and certain kidney tumours and cysts. Heavy smoking is associated with an increase in carbon monoxide in the blood and may also lead to higher red cell and hemoglobin levels. Low blood oxygen levels (hypoxia) due to congenital heart disease also appear to be a factor in the development of polycythemia.. Athletes, person going to gym, or involved in any heavy physical activities will be having high hemoglobin. Please consult a general physician first to rule out simple causes and to get some blood tests.