You're under 35 and feel fine, yet the doctor says your blood pressure is high and you'd better come back to have it checked again. Being a red-blooded male, you figure five years will be soon enough. After all, isn't high blood pressure an old man's disease?

"Young men are less likely than older men to believe they have hypertension and less likely to go back to the doctor," says Daniel Lackland, DrPH, spokesman for the American Society of Hypertension. "Often these are patients whose blood pressure would respond to weight management and other lifestyle changes, but they're less likely to seek treatment."

Untreated hypertension damages the heart and other organs and can lead to life-threatening conditions that include heart disease, stroke, and kidney disease. It's called "the silent killer" because symptoms generally appear only after the disease has caused damage to vital organs.

"With treatment, we can truly prolong life," Lackland tells WebMD.

Understanding High Blood Pressure

If your blood pressure is 120/80, 120 represents systolic pressure, or the pressure of blood against artery walls when the heart beats. Eighty represents diastolic pressure, or the pressure between beats.

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) guidelines categorize hypertension as follows:

Normal. Less than 120/80
Prehypertension. 120-139/80-89
Hypertension. 140/90 (130/80 for patients with diabetes or chronic kidney disease)
Stage 2 hypertension. 160/100

Hypertension, or high blood pressure (HBP), exists when either the systolic measurement is 140 or higher or the diastolic measurement is 90 or higher. However, in the majority of people, controlling systolic hypertension is a more important heart disease risk factor than diastolic blood pressure (except in young people under the age of 50).

There are two types of hypertension: essential, which accounts for 90% to 95% of cases, and secondary. The cause of essential hypertension is unknown, although lifestyle factors such as obesity, sedentary lifestyle, and excessive alcohol or salt intake contribute to the condition. In secondary hypertension, the cause may be kidney disease; hormonal imbalance; or drugs, including cocaine or alcohol.

According to the JNC 7, half the adult population is prehypertensive or hypertensive, and because blood pressure increases with age, most people will become hypertensive if they live long enough.

Younger vs. Older Men With High Blood Pressure

Younger men with high blood pressure typically have high diastolic pressure while older men have high systolic pressure. "In young men, the diastolic pressure rises because the heart is pumping harder," says Lackland. "In older men, the systolic pressure rises and stiffens arteries.

"Part of the problem with young men is increased body mass. Ten years ago we wouldn't have seen hypertension in the teens and 20s, but now it's increasing along with rising obesity rates. We're seeing the increase in particular in African-American men, but it affects men of all races."