Health professionals measure your blood pressure in millimeters of mercury. A high systolic blood pressure level is any number greater than 140. A high diastolic blood pressure level is any measurement bigger than 90. People who have measurements above these numbers, over two or more successive screenings, have stage one hypertension. Stage two hypertension is a diastolic measurement above 100 and a systolic blood pressure level of more than 160. People who have stage two hypertension at at serious risk and require immediate medical attention. Causes And Symptoms: High blood pressure levels do not always have a known...Finding out high blood pressure causes is probably the single most important step that you can take if you suffer from this problem. Nearly one third of Americans suffer, but many do not even know they have the condition. Many more have no idea what causes their high blood pressure or what treatment is available.