High Blood Pressure Causes, Symptoms, Risk Factors
- What is high blood pressure
- Categories for blood pressure levels
- Other names for high blood pressure
- Symptoms and consequences
- Causes and risk factors
Blood is carried from the heart to all parts of the body in vessels called arteries. When the heart pumps blood into the arteries (about 60–70 times a minute at rest), the blood flows with a force pushing against the walls of the arteries. This force is called the blood pressure. When the blood pressure is measured, it is a measure of how hard the heart has to work to pump the blood. The blood pressure is at its highest when the heart beats, pumping the blood. This is called systolic (sis-TOL-ik) pressure. When the heart is at rest, between beats, the blood pressure falls. This is the diastolic (di-a-STOL-ik) pressure.
Blood pressure is always given as these two numbers, the systolic and diastolic pressures. Usually they are written one above or before the other, such as 120/80 mmHg (measured in millimeters of mercury, a unit for measuring pressure). When the two measurements are written down, the systolic pressure is the first or top number, and the diastolic pressure is the second or bottom number (for example, 120/80). If the blood pressure is 120/80, it is said as "120 over 80."
High blood pressure or hypertension means high pressure (tension) in the arteries. Normal blood pressure is below 120/80; blood pressure between 120/80 and 139/89 is called “pre-hypertension”, and a blood pressure of 140/90 or above is considered high blood pressure.
Categories for blood pressure levels in adults (in mmHg, millimeters of mercury)
| Category | Systolic (top number) | Diastolic (bottom number) |
|---|---|---|
| Normal | Less than 120 | Less than 80 |
| Prehypertension | 120–139 | 80–89 |
| High blood pressure | ||
| Stage 1 | 140–159 | 90–99 |
| Stage 2 | 160 or higher | 100 or higher |
Note: When systolic and diastolic blood pressures fall into different categories, the higher category should be used to classify blood pressure level. For example, 160/80 mmHg would be stage 2 high blood pressure.
There is an exception to the above definition of high blood pressure. A blood pressure of 130/80 mmHg or higher is considered high blood pressure in people with diabetes and chronic kidney disease.
Other names for high blood pressure
General
- HBP
- Hypertension
- HTN
Caused by Another Condition
- Secondary hypertension
Other
- Essential hypertension
- Primary hypertension
- Idiopathic hypertension
Symptoms and consequences of high blood pressure
High blood pressure is a serious illness that affects about 72 million people age 20 and older in the United States. High blood pressure can occur in children or adults, but it's more common among people over age 35. It's particularly prevalent in African Americans, middle-aged and elderly people, obese people, heavy drinkers and women taking birth control pills. It may run in families, but many people with a strong family history of high blood pressure never have it. People with diabetes mellitus, gout or kidney disease are more likely to have high blood pressure, too.
Some people experience high blood pressure only when they visit the doctor's office. This condition is called "white-coat hypertension." If your doctor suspects this, you may be asked to monitor your blood pressure at home or asked to wear a device called an ambulatory blood pressure monitor. This device is usually worn for 24 hours and can take blood pressure every 30 minutes.
High blood pressure is often called the "silent killer" because it usually has no symptoms. Sometimes people with high blood pressure have the following symptoms:
- Headache
- Dizziness
- Blurred vision
- Nausea
The only way to tell whether you have high blood pressure is to have it measured with a blood pressure cuff (sphygmomanometer).
An elevation of the systolic and/or diastolic blood pressure increases the risk of developing heart (cardiac) disease, kidney (renal) disease, hardening of the arteries (atherosclerosis or arteriosclerosis), eye damage, and stroke (brain damage). These complications of hypertension are often referred to as end-organ damage because damage to these organs is the end result of chronic (long duration) high blood pressure.
Some people may not find out they have it until they have trouble with their heart, brain, or kidneys. When high blood pressure is not found and treated, it can cause:
- The heart to get larger, which may lead to heart failure.
- Small bulges (aneurysms (AN-u-risms)) to form in blood vessels. Common locations are the main artery from the heart (aorta); arteries in the brain, legs, and intestines; and the artery leading to the spleen.
- Blood vessels in the kidney to narrow, which may cause kidney failure.
- Arteries throughout the body to "harden" faster, especially those in the heart, brain, kidneys, and legs. This can cause a heart attack, stroke, kidney failure, or amputation of part of the leg.
- Blood vessels in the eyes to burst or bleed, which may cause vision changes and can result in blindness.
In 90 to 95 percent of high blood pressure cases, the American Heart Association says there's no identifiable cause. This type of high blood pressure, called essential hypertension or primary hypertension, tends to develop gradually over many years. And although the specific cause is unknown, certain factors are recognized as contributing to high blood pressure.
Factors that can't be changed
- Age. The risk of developing of high blood pressure increases as you get older, especially systolic, as your arteries get stiffer. This is largely due to arteriosclerosis, or "hardening of the arteries."
- Race. High blood pressure is particularly common among African Americans, often developing at an younger age. Serious complications, such as stroke and heart attack, also are more common in African Americans.
- Socioeconomic status. High blood pressure is also more common among the less educated and lower socioeconomic groups. Residents of the southeastern United States are more likely to have high blood pressure than Americans from other regions.
- Family history (heredity). The tendency to have high blood pressure appears to run in families.
- Sex. Generally men have a greater likelihood of developing high blood pressure than women. This likelihood varies according to age and among various ethnic groups.
Factors that can be changed
- Excessive weight (obesity). Obesity is defined as being 30% or more over your healthy body weight. It is very closely related to high blood pressure. Medical professionals strongly recommend that all obese people with high blood pressure lose weight until they are within 15% of their healthy body weight. The greater your body mass, the more blood you need to supply oxygen and nutrients to your tissues. As the volume of blood circulated through your blood vessels increases, so does the pressure on your artery walls.
- Inactivity. People who are inactive tend to have higher heart rates. The higher your heart rate, the harder your heart must work with each contraction - and the stronger the force on your arteries. Lack of physical activity also increases the risk of being overweight.
- Tobacco use. The chemicals in tobacco can damage the lining of your artery walls, which promotes narrowing of the arteries.
- Sodium intake. Some people have high sensitivity to sodium (salt), which can lead to fluid retention and increased blood pressure. Reducing sodium intake tends to lower their blood pressure. Americans consume 10-15 times more sodium than they need. Fast foods and processed foods contain particularly high amounts of sodium. Many over-the-counter medicines, such as painkillers, also contain large amounts of sodium.
- Low potassium intake. Potassium helps balance the amount of sodium in your cells. If you don't consume or retain enough potassium, you may accumulate too much sodium in your blood.
- Excessive alcohol. Drinking more than 1-2 drinks of alcohol per day tends to raise blood pressure in those who are sensitive to alcohol.
- Stress. High levels of stress can lead to a temporary but dramatic increase in blood pressure. If you try to relax by eating more, using tobacco or drinking alcohol, you may only fuel problems with high blood pressure.
- Birth control pills. Some women who take birth control pills develop high blood pressure.
- Drugs. Certain drugs, such as amphetamines (stimulants), diet pills, and some pills used for cold and allergy symptoms, tend to raise blood pressure.
The other 5 percent to 10 percent of high blood pressure cases are caused by an underlying condition. This type of high blood pressure, called secondary hypertension, tends to appear suddenly and cause higher blood pressure than does primary hypertension. Various conditions can lead to secondary hypertension, including kidney abnormalities, tumors of the adrenal gland or certain congenital heart defects.
- Renal (kidney) hypertension. Diseases of the kidneys can cause secondary hypertension. This type of secondary hypertension is called renal hypertension because it is caused by a problem in the kidneys.
- Adrenal gland tumors. Two rare types of tumors of the adrenal glands are less common, secondary causes of hypertension. (The adrenal glands sit right on top of the kidneys.) Both of these tumors produce excessive amounts of hormones (adrenal hormones) that cause high blood pressure.
- Coarctation of the aorta. Coarctation of the aorta is a rare hereditary disorder that is one of the most common causes of hypertension in children. This condition is characterized by a narrowing of a segment of the aorta, the main large artery coming from the heart.
Certain chronic conditions also may increase your risk of high blood pressure, including high cholesterol, diabetes and sleep apnea. Sometimes pregnancy contributes to high blood pressure.
More information about High Blood Pressure: