According to the seventh report by the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure (JNC 7), the optimal ranges for blood pressure readings are under 120 millimeters of mercury (mmHG) for systolic blood pressure, and under 80 mmHG for diastolic blood pressure. A person is considered “prehypertensive” if their systolic blood pressure measures 120 – 139 mmHG, or their diastolic blood pressure measures 80 – 89 mmHG.

If someone is diagnosed as “prehypertensive,” they have a substantially higher risk of developing hypertension. In fact, according to the Framingham Heart Study, individuals with measurements that fall between 130/80 and 139/89 have twice the risk of developing hypertension than people with blood pressure readings in the optimal range.

For patients with measurements higher than the prehypertension range, two stages of hypertension are designated by JNC 7. Stage 1 Hypertension is defined as a systolic measurement falling between 140 and 159 mmHG OR diastolic measurement falling between 90 and 99 mmHG. Stage 2 Hypertension is defined by systolic readings of 160 mmHG or higher, OR diastolic readings of 100 mmHG or higher.

The risk of cardiovascular disease, beginning at 115/75mmHG, doubles with each increase in blood pressure of 20/10 mmHG. This means that for every 20 point increase in systolic blood pressure and every 10 point increase in diastolic blood pressure, a patient’s risk of heart disease doubles. For example, if a patient’s blood pressure rose from 115/75 to 135/85, their risk for cardiovascular disease would have doubled.