Hypertension kills some 40,000 Americans each year, and another 200,000 die annually of a high-blood-pressure-related illness. People with hypertension are seven times more likely to have a stroke, six times more likely to have congestive heart failure, and three times more likely to develop a heart attack.

In all, hypertension claims more lives per year in the United States than cancer. Those numbers are doubly sad: first, because they are so high, and second, because they could easily be so much lower. More than half of the people with hypertension are not receiving treatment at all, and one-quarter of them are being inadequately treated. Only about one-fifth are receiving the proper treatment to control their blood pressure.

There are two types of hypertension. More than 90 percent of all cases of hypertension involve what is known as essential hypertension, which is high blood pressure without a definite cause. The rest, fewer than 10 percent of the cases, have a known cause; this is known as organic hypertension, or secondary hypertension. Organic hypertension occurs when a specific disease, such as a tumor of the kidneys, vascular disease, or hormonal disease, causes your blood pressure to be elevated.

When we talk about blood pressure, we are referring to a comparison of the blood pressure when the heart is beating versus the pressure when the heart is resting. A blood pressure reading is represented as the systolic (or beating pressure) over the diastolic (or resting) pressure. A normal blood pressure is anything lower than 120 over 80. But if you are 140 over 90 or above, you have high blood pressure. Anything in between the two sets of numbers is considered prehypertensive.

How can you tell you have high blood pressure? Certainly not by your symptoms; most people with hypertension don't have any. But any qualified health professional can measure your blood pressure in a very non-evasive way using a blood pressure machine. Of course, if your blood pressure is very high, you will have symptoms like nose bleeds, irregular heartbeats, headaches, and dizziness.

Hypertension affects more males than females and more blacks and Latinos than whites. The lifestyle characteristics that can put you at risk of developing hypertension include obesity, lack of exercise, a diet rich in sodium, and excessive alcohol consumption. Smoking raises blood pressure as well. Genetic factors may be involved, too, as some individuals have a family history of hypertension.

In younger women, hypertension is sometimes associated with birth control pills. Other medications that can give you high blood pressure include some nonsteroid anti-inflammatories, cold remedies, decongestants, and appetite-suppressant pills.