Blood pressure has two components:
- Systolic pressure is the top number. It represents the pressure the heart generates when it beats to pump blood to the rest of the body.
- Diastolic pressure is the bottom number. It refers to the pressure in the blood vessels between heartbeats.
Blood pressure is measured in millimeters of mercury (mm Hg). So blood pressure would be expressed, for example, as 120/80 mm Hg.
High blood pressure is diagnosed when one or both of these numbers is too high. High blood pressure is also called hypertension.
For decades, high blood pressure was defined as 140/90 mm Hg. In November, 2017, new United States guidelines lowered the threshold for diagnosing the condition. According to new guidelines, anyone with a reading of 130/80 mm Hg or higher has blood pressure. Based on this new definition, nearly half of Americans now fall into this group.
Blood pressure is now categorized as follows:
Normal: Less than 120/80 mm Hg
Elevated: 120/80 to 129/79 mm Hg
Stage 1 hypertension: 130/80 to 139/89 mm Hg
Stage 2 hypertension: 140/90 mm Hg and above
Although high blood pressure can cause symptoms such as headache and pounding heartbeat, it often causes no symptoms at all.
So why worry about high blood pressure? Because even when high blood pressure is not causing any symptoms, it can silently damage many organs, including the:
- Brain
- Eyes
- Heart
- Kidneys
- Arteries throughout the body
You may not recognize the damage that silent hypertension has been doing to your body until you suddenly are stricken with a major disease. For example, hypertension increases your risk of heart attack, stroke, and kidney failure.