What is hyperlipidemia?
Hyperlipidemia is an elevation of lipids (fats) in the
bloodstream. These lipids include cholesterol, cholesterol
esters (compounds), phospholipids and triglycerides. They're
transported in the blood as part of large molecules called
These are the five major families of blood (plasma)
2 very low-density lipoproteins (VLDL)
3 intermediate-density lipoproteins (IDL)
4 low-density lipoproteins (LDL)
5 high-density lipoproteins (HDL)
What are the types of hyperlipidemia?
When hyperlipidemia is defined in terms of a class or classes of
elevated lipoproteins in the blood, the term
hyperlipoproteinemia is used. Hypercholesterolemia is the term
for high cholesterol levels in the blood. Hypertriglyceridemia
refers to high triglyceride levels in the blood.
What is cholesterol?
Cholesterol is a soft, waxy substance found among the lipids
(fats) in the bloodstream and in all your body's cells. It's an
important part of a healthy body because it's used to form cell
membranes, some hormones and is needed for other functions. But
a high level of cholesterol in the blood -- hypercholesterolemia
-- is a major risk factor for coronary heart disease, which
leads to heart attack.
Cholesterol and other fats can't dissolve in the blood. They
have to be transported to and from the cells by special carriers
called lipoproteins. There are several kinds, but the ones to
focus on are low-density lipoprotein (LDL) and high-density
What is LDL cholesterol?
Low-density lipoprotein is the major cholesterol carrier in the
blood. If too much LDL cholesterol circulates in the blood, it
can slowly build up in the walls of the arteries feeding the
heart and brain. Together with other substances it can form
plaque, a thick, hard deposit that can clog those arteries. This
condition is known as atherosclerosis. A clot (thrombus) that
forms near this plaque can block the blood flow to part of the
heart muscle and cause a heart attack. If a clot blocks the
blood flow to part of the brain, a stroke results. A high level
of LDL cholesterol (160 mg/dL and above, or 4.2 mM and above)
has been shown conclusively to reflect an increased risk of
heart disease. That's why LDL cholesterol is called "bad"
cholesterol. Lower levels of LDL cholesterol reflect a lower
risk of heart disease.
What is HDL cholesterol?
About one-third to one-fourth of blood cholesterol is carried by
HDL. Medical experts think HDL tends to carry cholesterol away
from the arteries and back to the liver, where it's passed from
the body. Some experts believe HDL removes excess cholesterol
from plaques and thus slows their growth. HDL cholesterol is
known as "good" cholesterol because a high HDL level seems to
protect against heart attack. The opposite is also true: a low
HDL level (less than 40 mg/dL or 1.0 mM) indicates a greater
risk. A low HDL cholesterol level also may raise stroke risk.
What about cholesterol and diet?
People get cholesterol in two ways. The body -- mainly the liver
-- produces varying amounts, usually about 1,000 milligrams a
day. Foods also can contain cholesterol. Foods from animals
(especially egg yolks, meat, poultry, fish, seafood and
whole-milk dairy products) contain it. Foods from plants
(fruits, vegetables, grains, nuts and seeds) don't contain
Typically the body makes all the cholesterol it needs, so people
don't need to consume it. Saturated fatty acids are the main
culprit in raising blood cholesterol, which increases your risk
of heart disease. Trans-fats also raise blood cholesterol. But
dietary cholesterol also plays a part. The average American man
consumes about 337 milligrams of cholesterol a day; the average
woman, 217 milligrams.
Some of the excess dietary cholesterol is removed from the body
through the liver. Still, it is recommended that you limit your
average daily cholesterol intake to less than 300 milligrams. If
you have heart disease, limit your daily intake to less than 200
milligrams. Still, everyone should remember that by keeping
their dietary intake of saturated fats low, they can
significantly lower their dietary cholesterol intake. Foods high
in saturated fat generally contain substantial amounts of
People with severe high blood cholesterol levels may need an
even greater reduction. Since cholesterol is in all foods from
animal sources, care must be taken to eat no more than six
ounces of lean meat, fish and poultry per day and to use
fat-free and low-fat dairy products. High-quality proteins from
vegetable sources such as beans are good substitutes for animal
sources of protein.
How does exercise (physical activity)
Consistent exercise increases HDL cholesterol in some people. A
higher HDL cholesterol is linked with a lower risk of heart
disease. Exercise can also help control weight, diabetes and
high blood pressure. Exercise that uses oxygen to provide energy
to large muscles (aerobic exercise) raises your heart and
breathing rates. Regular moderate to intense exercise such as
brisk walking, jogging and swimming also condition your heart
Physical inactivity is a major risk factor for heart disease.
Even moderate-intensity activities, if done daily, help reduce
your risk. Examples are walking for pleasure, gardening, yard
work, housework, dancing and prescribed home exercise.
How does tobacco smoke affect
Tobacco smoke is one of the six major risk factors of heart
disease that you can change or treat. Smoking lowers HDL
How does alcohol affect cholesterol?
In some studies, moderate use of alcohol is linked with higher
HDL cholesterol levels. However, because of other risks, the
benefit isn't great enough to recommend drinking alcohol if you
don't do so already. People with diabetes should be careful
about embracing this belief without consulting their doctors.
If you drink, do so in moderation. People who consume moderate
amounts of alcohol (an average of one to two drinks per day for
men and one drink per day for women) have a lower risk of heart
disease than nondrinkers. However, increased consumption of
alcohol brings other health dangers, such as alcoholism, high
blood pressure, obesity, stroke, cancer, suicide, etc. Given
these and other risks, we caution people against increasing
their alcohol intake or starting to drink if they don't already
Drug therapy can be considered for patients who, in spite of
adequate dietary therapy, regular physical activity and weight
loss, need further treatment for elevated blood cholesterol
levels. The guidelines for those who qualify are:
If you do not have coronary heart disease and have fewer than
two risk factors, drugs should be used if your LDL is 190 mg/dL
(5.0 mM) or higher*. The goal is to lower LDL to less than 160
mg/dL or 4.2 mM.
If you don not have coronary heart disease but have two or more
risk factors, drugs should be used if your LDL is 160 mg/dL (4.2
mM) or higher. the goal is to lower LDL to less than 130 mg/dL
If you have coronary heart disease or diabetes, drugs should be
used if your LDL is 130 mg/dL (3.3 mM) or higher**. The goal is
to lower LDL to 100 mg/dL (2.6 mM) or less.
* In men less than 35 years of age and premenopausal women with
LDL cholesterol levels of 190 to 219 mg/dL, drug therapy should
be delayed except in high-risk patients such as those with
** In coronary heart disease patients with LDL cholesterol
levels of 100 to 129 mg/dL, the physician should exercise
clinical judgment in deciding whether to begin drug treatment.
In some cases, a physician may decide that using
cholesterol-lowering drugs at lower LDL cholesterol levels is
justified. On the other hand, drug therapy may not be
appropriate for some patients who meet the above criteria. This
may be true for elderly patients.
The presence of other coronary heart disease risk factors
influences the use of cholesterol-lowering drugs:
1 age (for men, 45 years or older; for women, 55 years or older
OR premature menopause)
2 family history of premature heart disease (a father, brother
or son with a history of coronary heart disease before age 55,
OR a mother, sister or daughter with CHD before age 65)
3 smoking OR living or working every day with people who smoke
4 high blood pressure (140/90 mm Hg or higher)
5 HDL cholesterol less than 40 mg/dL
What drugs are most commonly used to
treat high cholesterol?
The drugs of first choice for elevated LDL cholesterol are the
HMG CoA reductase inhibitors, e.g., lovastatin, pravastatin and
simvastatin and atorvastatin. Statin drugs are very effective
for lowering LDL cholesterol levels and have few immediate
short-term side effects. They are easy to administer, have high
patient acceptance and have few drug-drug interactions. Patients
who are pregnant, have active or chronic liver disease, or who
are allergic to statins shouldn't use statin drugs. The most
common side effects are gastrointestinal, including constipation
and abdominal pain and cramps. These symptoms are usually mild
to severe and generally subside as therapy continues.
Another class of drugs for lowering LDL is the bile acid
sequestrants -- cholestyramine and colestipol -- and nicotinic
acid (niacin). These have been shown to reduce the risk for
coronary heart disease in controlled clinical trials. Both
classes of drugs appear to be free of serious side effects. But
both can have troublesome side effects and require considerable
patient education to achieve adherence. Nicotinic acid is
preferred in patients with triglyceride levels that exceed 250
mg/dL because bile acid sequestrants tend to raise triglyceride
What other drugs are available to treat
Other available drugs are gemfibrozil, probucol and clofibrate.
Gemfibrozil and clofibrate are most effective for lowering high
If a patient doesn't respond adequately to single drug therapy,
combined drug therapy should be considered to further lower LDL
cholesterol levels. For patients with severe
hypercholesterolemia, combining a bile acid sequestrant with
either nicotinic acid or lovastatin has the potential to
markedly lower LDL cholesterol. For hypercholesterolemic
patients with elevated triglycerides, nicotinic acid or
gemfibrozil should be considered as one agent for combined
What are triglycerides?
Triglycerides are the chemical form in which most fat exists in
food as well as in the body. They're also present in blood
plasma and, in association with cholesterol, form the plasma
Triglycerides in plasma are derived from fats eaten in foods or
made in the body from other energy sources like carbohydrates.
Calories ingested in a meal and not used immediately by tissues
are converted to triglycerides and transported to fat cells to
be stored. Hormones regulate the release of triglycerides from
fat tissue so they meet the body's needs for energy between
How is an excess of triglycerides
Excess triglycerides in plasma is called hypertriglyceridemia.
It's linked to the occurrence of coronary artery disease in some
people. Elevated triglycerides may be a consequence of other
disease, such as untreated diabetes mellitus. Like cholesterol,
increases in triglyceride levels can be detected by plasma
measurements. These measurements should be made after an
overnight food and alcohol fast.
The National Cholesterol Education Program guidelines for
Normal Less than 150 mg/dL
Borderline-high 150 to 199 mg/dL
High 200 to 499 mg/dL
Very high 500 mg/dL or higher
These are based on fasting plasma triglyceride levels.
Dietary treatment goals
Changes in lifestyle habits are the main therapy for
hypertriglyceridemia. These are the changes you need to make:
1 If you're overweight, cut down on calories to reach your ideal
body weight. This includes all sources of calories, from fats,
proteins, carbohydrates and alcohol.
2 Reduce the saturated fat and cholesterol content of your diet.
3 Reduce your intake of alcohol considerably. Even small amounts
of alcohol can lead to large changes in plasma triglyceride
4 Be physically active for at least 30 minutes on most days each
5 People with high triglycerides may need to substitute
monounsaturated and polyunsaturated fats -- such as those found
in canola oil, olive oil or liquid margarine -- for saturated
fats. Substituting carbohydrates for fats may raise triglyceride
levels and may decrease HDL ("good") cholesterol in some people.
6 Substitute fish high in omega-3 fatty acids instead of meats
that are high in saturated fat like hamburger. Fatty fish like
mackerel, lake trout, herring, sardines, albacore tuna and
salmon are high in omega-3 fatty acids.
7 Because other risk factors for coronary artery disease
multiply the hazard from hyperlipidemia, control high blood
pressure and avoid cigarette smoking. If drugs are used to treat
hypertriglyceridemia, dietary management is still important.
Patients should follow the specific plans laid out by their
physicians and nutritionists. Drugs that lower triglycerides
belong to the fibrate class.