Every two to three years if it's normal. Follow your physician's advice if it's not.

Blood pressure can drop when temperatures rise. Vessels dilate when it's hot and constrict when it's cold.

Because it has no obvious symptoms, hypertension is called the silent killer.

A direct cause isn't known in 90 percent of cases, however.

140 over 90 indicates Stage one hypertension. A blood pressure of 120/80 to 129/89 is termed prehypertension. Normal blood pressure is less than 120/80. If either the systolic (higher number) or diastolic (lower number) is in one of the ranges listed above, that is the category that you are in. So, for example, if you blood pressure were 122/70 consistently, you would be called prehypertensive.

Over time, high blood pressure damages blood vessels (conditions called arteriosclerosis and atherosclerosis), causing an increased risk for not only stroke, but also heart attacks and kidney disease.

Excessive drinking increases heart rate, which puts pressure on vessel walls. Three to five drinks a day over a long period can cause hypertension.

Aging directly correlates to an increase in risk.

People who are sensitive to salt have blood pressure that reacts significantly to salt. The USDA Dietary Guidelines recommend that sodium (salt) be limited to less than 2,300 mg (about one teaspoon) a day.

Although you can't change certain risk factors such as age and family health history, you can choose a lifestyle that promotes heart health.