High Blood Cholesterol
Provided by: Mayo Clinic.com last Updated: 09/29/2005

Overview

Because of its reputation as a risk factor for heart disease, people tend to think of cholesterol only in
negative terms. But cholesterol is an important component of cell membranes and is vital to the structure
and function of all of your body's cells. Cholesterol also is a building block in the formation of certain
types of hormones.

Still, 37 million American adults have high blood cholesterol levels, and 105 million have cholesterol
levels that are higher than desirable (hypercholesterolemia). If you're one of these people with this
largely preventable condition, you may be on your way to heart disease.

When the levels of cholesterol and triglycerides, a blood fat, in your bloodstream become too high, your
likelihood of developing cholesterol-containing fatty deposits (plaques) in your blood vessels increases.
Over time, plaques cause your arteries to narrow, which impedes blood flow and creates a condition
called atherosclerosis. Narrowing of the arteries that supply your heart with blood (coronary artery
disease) can prevent your heart from getting as much oxygen-rich blood as it needs. This means an
increased risk of a heart attack. Likewise, decreased blood flow to your brain can cause a stroke. Less
blood flowing to your lower limbs may result in exercise-related pain or even gangrene.

The good news is that with the help of lifestyle changes and possibly medications, you may be able to
lower your high blood cholesterol. It's estimated that if there were a 10 percent reduction in cholesterol
levels throughout the U.S. population, the rate of heart disease would drop by 30 percent.


Signs and symptoms

There are no symptoms of high blood cholesterol. The only way to find out if you have high blood
cholesterol is by having a blood test.


Causes

To circulate in your blood, which is mainly water, cholesterol and triglycerides a form of fat must be
carried by proteins called apoproteins. A lipoprotein is a combination of a lipid a fatty substance in the
blood and an apoprotein.

The main types of lipoproteins are:

  • Low-density lipoprotein (LDL). LDL cholesterol is sometimes called "bad" cholesterol
    because it transports cholesterol to sites throughout your body, where it's either deposited or used
    to repair cell membranes. But like hard water causing lime to build up inside plumbing, LDL
    cholesterol promotes accumulation of cholesterol in the walls of your arteries.
  • High-density lipoprotein (HDL). HDL cholesterol is sometimes referred to as "good"
    cholesterol because it helps clear excess cholesterol from your body.
  • Very-low-density lipoprotein (VLDL). This type of lipoprotein is made up of mostly
    triglycerides and small amounts of protein and cholesterol.

Having a low level of LDL cholesterol and a high level of HDL cholesterol is desirable for lowering your
risk of developing plaques and coronary artery disease.

You may have high LDL cholesterol as a result of genetic makeup or lifestyle choices, or both. Your genes
can give you cells that don't remove LDL cholesterol from your blood efficiently or a liver that produces
too much cholesterol as VLDL particles. Your genetic makeup can also result in too few HDL particles.


Risk factors

These lifestyle choices can cause or contribute to high levels of total cholesterol:

  • Inactivity. Lack of exercise may lower your level of HDL cholesterol.

  • Obesity. Excess weight increases your triglycerides. It also lowers your HDL cholesterol and
    increases your VLDL cholesterol. Being overweight can create a more serious risk factor for health
    problems depending on how you carry the extra weight. If you carry most of your fat around your
    waist or upper body, you may be referred to as apple-shaped. If you carry most of your fat around
    your hips and thighs or lower body, you're considered to be pear-shaped. Generally, when it comes
    to your health, it's better to have the shape of a pear than the shape of an apple. If you have an
    apple shape a potbelly or spare tire you carry more fat in and around your abdominal organs.
    Fat in your abdomen increases your risk of many of the serious conditions associated with obesity.
    A woman's waist should measure less than 35 inches. A man's waist should be less than 40 inches.

  • Diet. Cholesterol naturally occurs in foods derived from animals, such as meat, eggs and cheese.
    Eating a high-fat, high-cholesterol diet contributes to an increased blood cholesterol level.
    Saturated and trans fats raise blood cholesterol levels. Polyunsaturated fats lower blood
    cholesterol, but also seem susceptible to oxidation. Over time, oxidation speeds buildup of plaques
    inside your arteries. Monounsaturated fats may help lower blood cholesterol and are resistant to
    oxidation.

    These factors increase the likelihood that high total cholesterol levels will lead to atherosclerosis:

  • Smoking. Cigarette smoking damages the walls of your blood vessels, making them likely to
    accumulate fatty deposits. Smoking may also lower your level of HDL cholesterol.
  • High blood pressure. By damaging the walls of your arteries, high blood pressure can accelerate
    the accumulation of fatty deposits on the walls of your arteries.
  • Type 2 diabetes. This type of diabetes results in a buildup of sugar levels in your blood. Chronic
    high blood sugar may lead to narrowing of your arteries. If you have diabetes, controlling your
    cholesterol and triglyceride levels may greatly reduce your risk of complications from
    cardiovascular disease.
  • Family history of atherosclerosis. If a close family member (parent or sibling) has developed
    atherosclerosis before age 55, high cholesterol levels place you at a greater than average risk of
    developing atherosclerosis.


Screening and diagnosis

A good way to detect high blood cholesterol early, so that you can take steps to improve your health, is to
have a regular blood test to measure your cholesterol level. A blood test to check cholesterol levels
typically measures:

HDL cholesterol
LDL cholesterol
Total cholesterol
Triglycerides

To measure cholesterol subtypes accurately, this test called a lipid panel or lipid profile requires that
you avoid eating or drinking anything (other than water) for nine to 12 hours before your blood is drawn.

Interpreting the numbers

Cholesterol levels are measured in milligrams (mg) of cholesterol per deciliter (dL) of blood. But what are
the optimal levels of these various lipids? The following tables from the National Heart, Lung, and Blood
Institute offer general guidelines.

Total cholesterol
Below 200 mg/dL Desirable
200-239 mg/dL Borderline high
240 mg/dL and above High

LDL cholesterol
Below 100 mg/dL Optimal
100-129 mg/dL Near optimal
130-159 mg/dL Borderline high
160-189 mg/dL High
190 mg/dL and above Very high

HDL cholesterol
Below 40 mg/dL Bad
40-59 mg/dL Better
60 mg/dL and above Best

Triglycerides
Below 150 mg/dL Desirable
150-199 mg/dL Borderline high
200-499 mg/dL High
500 or above Very high



LDL targets differ
Because LDL cholesterol has a major association with heart disease, it's the main focus of cholesterol-
lowering treatment. So it's important to know your LDL target number. The problem is that this target
can vary, depending on your underlying risk of heart disease.

People at low risk of heart disease may be fine with an LDL level of 160 mg/dL. Those with a slightly
higher risk should probably aim lower to reach 130 mg/dL. And while an LDL level under 100 mg/dL
seems to be good for most people, some people at very high risk may need to try to get their LDL number
under 70 mg/dL.

Are you at very high risk? You might be if you have had a heart attack in the past or if you have diabetes.
You may also be in the very high risk group if you have two or more of the following risk factors:

  • Smoking
  • High blood pressure
  • Low HDL cholesterol
  • Family history of early onset heart disease
  • Age older than 45 if you're a man, or older than 55 if you're a woman


How often should you be tested?

Have your baseline cholesterol tested when you're in your 20s and then at least every five years. If your
values aren't within desirable ranges, your doctor may advise more frequent measurements.

You can also purchase a home cholesterol test. These tests measure only total cholesterol, are less
sophisticated than laboratory tests and may give unreliable results.

Children generally don't need to undergo cholesterol testing, unless there's a family history of early-onset
heart problems.

Complications

High blood cholesterol can cause you to develop heart disease. The American Heart Association reports
that heart disease kills over 1.4 million Americans each year, more than all cancer deaths combined.
Many of these deaths occur because of the accumulation of fatty deposits (plaques) on the walls of your
arteries (atherosclerosis), resulting in narrowed or blocked arteries. Cholesterol plays a significant role in
this largely preventable condition.

Atherosclerosis is initially a silent, painless condition that results in reduced blood flow. If reduced flow
occurs in the arteries that supply your heart with blood (coronary arteries), it can lead to a type of chest
pain called angina pectoris.

As a plaque enlarges, the inner lining of your artery becomes roughened. A tear or rupture in the plaque
may cause a blood clot to form. Such a clot can block the flow of blood or break free and plug an artery
downstream.

If the flow of blood to a part of your heart is stopped, you'll have a heart attack. If blood flow to a part of
your brain stops, a stroke occurs.

High blood cholesterol along with high blood pressure, insulin resistance and obesity are factors that
make up metabolic syndrome, a combination of disorders which greatly increases your risk of developing
heart disease, stroke or diabetes.

Having a high number of cholesterol particles (lipoproteins) in your blood increases your risk of a
buildup of cholesterol within the wall of your artery. Eventually, bumps called plaques may form,
narrowing or even blocking your artery.

Treatment

Lifestyle changes are the first steps you can take to improve your blood levels of cholesterol and
triglycerides. These include changes in diet, regular exercise and avoiding smoking. If you've made these
important lifestyle changes and your total cholesterol especially your level of LDL cholesterol
remains high, your doctor may recommend prescription medication.

Before recommending medication, your doctor may weigh many variables your changeable risk
factors, your age, your current health and the drug's side effects. If you need a medication to improve
your cholesterol levels, chances are you may need it for many years.Your LDL cholesterol level is usually
the deciding factor.

Medications to improve blood cholesterol levels include:

  • Resins. The medications cholestyramine (Questran) and colestipol (Colestid) lower cholesterol
    indirectly by binding to bile acids in your intestinal tract. Your liver makes bile acids, which you
    need for digestion, from cholesterol. By tying up bile acids, resins prompt your liver to make more
    bile acids. Because your liver uses cholesterol to make bile acids, less cholesterol is available to
    reach your bloodstream.
  • Triglyceride-lowering drugs. These medications include fibrates such as gemfibrozil (Lopid)
    and fenofibrate (Tricor), and niacin (nicotinic acid). Fibrates reduce triglyceride production and
    remove triglycerides from circulation. They can also increase your HDL cholesterol level.
  • Statins. Statins work directly in your liver to block a substance your liver needs to make
    cholesterol. This depletes cholesterol in your liver cells, which causes your liver cells to remove
    cholesterol from your blood. Statins may also help your body reabsorb cholesterol from plaques
    that accumulate on the walls of your arteries. Statins include fluvastatin (Lescol), lovastatin
    (Mevacor), simvastatin (Zocor), pravastatin (Pravachol), atorvastatin (Lipitor) and rosuvastatin
    (Crestor).
  • Cholesterol absorption inhibitor. Your small intestine absorbs the cholesterol from your
    diet. After that, dietary cholesterol enters the bloodstream. Your total cholesterol is the result of
    dietary cholesterol and the cholesterol the liver produces itself. The drug ezetimibe (Zetia) helps
    reduce blood cholesterol by limiting the absorption of dietary cholesterol.
  • Cholesterol absorption inhibitor-plus-statin combination. The combination drug
    ezetimibe/simvastatin (Vytorin) decreases both absorption of dietary cholesterol in your small
    intestine and production of cholesterol in your liver.


Prevention

Improving your blood cholesterol levels reduces your risk of heart disease. Lifestyle changes are your
first course of action to improve your blood cholesterol levels. These approaches include eating a healthy
diet, exercising and not smoking.

Eating a healthy diet
These changes in your diet can improve your blood cholesterol levels:

  • Control total fat. Limit all types of fat saturated, polyunsaturated, trans fatty acids (trans fats)
    and monounsaturated to no more than 30 percent of your total daily calories. Because all foods
    with fats contain a combination of these fats, it's important to reduce total fat. Not every food you
    eat must have less than 30 percent of its calories from fat. Use the guideline as a daily average. By
    balancing occasional high-fat foods with low-fat choices, your fat intake should average no more
    than 30 percent of your daily calories. If your daily intake is 2,000 calories, 30 percent equals 65
    grams of fat. Limit saturated fat to no more than 10 percent of total calories.
  • Limit dietary cholesterol. Your daily limit for dietary cholesterol is 300 milligrams, or less
    than 200 milligrams if you have heart disease. To accomplish this goal, limit or avoid concentrated
    sources such as organ meats, egg yolks and whole-milk products.
  • Eat foods with soluble fiber. As part of a low-fat diet, soluble fiber can help lower your total
    blood cholesterol level. Foods high in soluble fiber include oat bran, oatmeal, beans, peas, rice
    bran, barley, citrus fruits, strawberries and apple pulp.
  • Eat more fish. Some fish particularly fatty types prevalent in cold water, such as salmon,
    mackerel and herring contain high amounts of a unique type of polyunsaturated fat called
    omega-3 fatty acids. Omega-3s may lower your level of triglycerides. However, pregnant women,
    women who are breast-feeding and women who plan to become pregnant in the next several years,
    and young children should not eat king mackerel, shark, swordfish or tilefish. They should also
    limit their weekly intake of albacore tuna and locally caught fish, according to the Food and Drug
    Administration. Salmon, canned light tuna, pollock, shrimp and catfish are generally low in
    mercury.
  • Consider soy products. Soy compounds called isoflavones act like human hormones that
    regulate cholesterol levels. Eating soy proteins can reduce your levels of total cholesterol, LDL
    cholesterol and triglycerides. Eating soy may also raise your level of HDL cholesterol, which may
    protect you against heart disease.
  • Drink alcohol in moderation, if at all. Moderate consumption of alcohol may raise your
    level of HDL cholesterol. The best advice is to drink in moderation, if you drink at all. Limit alcohol
    to one drink daily if you're a woman or to no more than two drinks daily if you're a man. If you're a
    nondrinker, don't start drinking alcohol. Don't drink alcohol if you have a high level of
    triglycerides.
  • Reduce sugar intake. This is a way of lowering triglyceride levels. Ideally, your triglyceride
    levels should be lower than 150 mg/dL.

Exercising

Being overweight promotes a high total cholesterol level. Losing weight improves your cholesterol levels.
Set up an exercise program to lose weight using these guidelines and your doctor's advice:

  • Choose an aerobic activity. Get involved in activities such as brisk walking, jogging, bicycling
    or cross-country skiing.
  • Build up the time and frequency of exercising. Gradually work up to exercising for 30
    minutes to 45 minutes at least three times a week. If you're overweight or have been inactive for
    many years, take several months to work up gradually to this level. The higher the level of your
    activity, the greater your rate of weight loss.
  • Stick with your exercise program. Schedule a regular time for exercise. Make exercise fun. If
    it's not enjoyable, you may not feel like exercising regularly year in, year out. Find a friend or join
    an exercise group to keep you motivated and committed to exercise. Or take up an activity that
    keeps you active.

Not smoking

If you smoke, stop. If you don't smoke, don't start. Cigarette smoking damages the walls of your blood
vessels, making them prone to accumulating fatty deposits. If you stop smoking, your HDL cholesterol
may return to its former level.
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