The National Heart Blood and Lung Institute, or NHBLI, estimates that 50 million people in the United States have hypertension, commonly known as high blood pressure. The NHBLI adds that as blood pressure increases, so does the risk of suffering a heart attack, heart failure, stroke or kidney disease. Hypertension is divided into four stages.
Normal
When the heart beats, there is a maximum pressure--called the systolic pressure--exerted by the blood against the vessel walls, seen as the top number in a reading, and a minimum pressure--the diastolic--as the bottom number in a reading. It is measured in millimeters of mercury, or mmHg. A blood pressure of 120 mmHg or less, over 80 mmHg or less, is considered by the NHBLI to be normal. According to a 2006 article published in the "Chinese Medical Journal," hypertension occurs above this value. The Framingham Heart Study, an ongoing study since 1948 by the NHBLI and Boston University, found that people who have normal blood pressure at age 55 still have a 90 percent risk of becoming hypertensive sometime during their life.
Prehypertension
The NHBLI considers a reading of 120 to 139 mmHg over 80 to 89 mmHg as prehypertensive. It recommends at this stage a modification in lifestyle around diet and exercise, including weight control, decreased sodium intake, increased physical activity and moderate alcohol consumption, as well as drug therapy if kidney disease or diabetes is also present.
Stage 1 Hypertension
Stage 1 hypertension is indicated by blood pressure readings of 140 to 159 mmHg over 90 to 99 mmHg, notes the NHBLI. People who fall within this category require a change in lifestyle, and a thiazide-type medication is usually prescribed. Thiazides are diuretics and encourage the passing of fluids through the kidney. They also tend to widen, or dilate, the blood vessels. The combination effectively reduces blood pressure. If a pre-existing condition is present, antihypertensive drugs may be indicated with or without a thiazide.
Stage 2 Hypertension
Anything greater than 160 mmHg over 100 mmHg is stage 2 hypertension. Indicated treatment advised by the NHBLI is a combination of both an antihypertensive drug and a thiazide. The NHBLI also notes that for each increment of 20 mmHg in systolic blood pressure or 10 mmHg in diastolic blood pressure in individuals 40 to 70 years of age doubles the risk of cardiovascular disease.
