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From the Fall 2004 Issue

You Asked. We Answered.

The Basics About Cholesterol Testing

You've been told you have a total cholesterol level of 220. But is that too low? OK? Too high? Good cholesterol and bad cholesterol—which is LDL and which is HDL? And what do those abbreviations mean, anyway?

Cholesterol is substance made by the body. You probably know that too much cholesterol is not good. But your body needs a certain amount of cholesterol to function properly. Some people have too much cholesterol in their blood because of their family history. But many people have too much cholesterol because of their lifestyles, especially too little exercise and too many high-fat foods from animal sources. LifeBeat Online answers your questions about cholesterol testing.

Why should I have a cholesterol test?

High cholesterol is a risk factor for cardiovascular diseases, such as heart disease, heart attack, or stroke. The more cholesterol floating in the blood, the more likely that plaque will build up on your artery walls and lead to problems. During your regular checkups, your doctor may order a blood test to measure cholesterol. The cholesterol test is a good indicator of whether you are at risk for developing blocked arteries.

There are no early warning signs or symptoms of high cholesterol. To know whether your cholesterol is too high, your doctor has to look at fat levels, also called lipid levels, in your blood. A family history of heart disease can increase your risk for high cholesterol.

Keeping your cholesterol under control can reduce the risk of:

• Blocked arteries
• Dying from heart disease
• Having a heart attack
• Needing heart bypass surgery or angioplasty (to clear blocked arteries)
• Having a stroke

Fasting (not eating anything, and drinking only water) is required before the cholesterol test. Your doctor or nurse will tell you how long you should fast before your test.

Exactly what is tested during a cholesterol test?

The cholesterol test measures different forms of fats in your blood. To be circulated in your blood, fats must attach to proteins. You'll hear the term "lipoprotein" in reference to cholesterol. A lipoprotein carries the fats or lipids in your blood.

The cholesterol test, also called a lipid panel or lipid profile, requires a sample of your blood to measure:

• Total cholesterol
• Low-density lipoproteins (LDL), known as "bad" cholesterol
• High-density lipoproteins (HDL), known as "good" cholesterol
• Triglycerides

What are the desired cholesterol levels?

The cholesterol test provides four readings. (Cholesterol is measured in milligrams per deciliter of blood, or mg/dL.) The target levels¹ are:

• Total cholesterol—less than 200
• LDL ("bad")—less than 100
• HDL ("good")—40 or higher
• Triglycerides—less than 150

However, your overall risk factors (such as family history of heart disease) will affect your doctor's opinion about whether your cholesterol is acceptable or too high. For example, if your doctor believes that you're at very high risk of heart disease, he or she might set your target LDL level at less than 70.

What is the difference between bad and good cholesterol?

LDL or Bad Cholesterol

In low amounts, LDL or bad cholesterol helps repair cell membranes. But in larger amounts, it sticks to the sides of your blood vessels. As more cholesterol is deposited, plaque forms.

Plaque is a hardened substance formed from LDL and other fats in your blood. Plaque makes your arteries:

• Narrowed
• More rigid or harder (called atherosclerosis or hardening of the arteries)

HDL or Good Cholesterol

HDL is known as good cholesterol because it actually removes from your blood some of the cholesterol deposits left by LDL. This action by HDL:

• Prevents blockages from forming or getting larger
• Helps keep your blood moving freely

HDL carries cholesterol to the liver, where it's eventually passed out of the body. About one-fourth to one-third of cholesterol is HDL.

Note that you cannot figure out your HDL or LDL levels just from knowing your total cholesterol level. The formula for calculating the ratio between HDL and LDL levels based on your total cholesterol level is complex and must be performed by a medical laboratory. The bottom line is that it's best to have a high HDL level and a low LDL level.

What are triglycerides?

Triglycerides are the most common fat in the body. They are usually found in fat tissue, but certain amounts are also found in your blood.

Your body makes triglycerides from excess calories that you eat or drink. They are stored in fat cells to be used later as energy.

If you have either low HDL or high LDL, and a high triglyceride level in your blood, you may develop:

• Cholesterol deposits in your arteries
• Plaque
• Blocked arteries

How does high cholesterol contribute to heart disease?

As arteries are narrowed and hardened with cholesterol and plaque buildup, blood flow is slowed. As the blood pools behind the narrowed spot in the artery, blood clots are more likely to form. Plaque can burst and also create a blood clot.

A blood clot can be very dangerous, depending on where it travels:

• If it travels to the heart, it can cause a heart attack.
• If it travels to the brain, it can cause a stroke.

What can I do to improve my cholesterol level?

Following healthy lifestyle guidelines is the first step in helping to lower your cholesterol, and thus help protect you from cardiovascular disease.

• Eat a low-fat diet:
• Avoid high-fat foods (egg yolks, nonlean meats, butter, oil, and whole-milk dairy products)
• Eat more fruits, vegetables, and whole grains (for example, oatmeal, brown rice, or barley)
• To get your protein, substitute beans—or very lean meats such as the white meat from poultry—for higher fat meat products.
• Do aerobic exercise (the kind that gets your heart rate up) for 30 minutes or longer at least four days a week.
• Maintain a healthy weight.
• Don't smoke! Smoking damages your artery walls, lowers HDL levels, and promotes cholesterol deposits and plaque formation.
• Keep your blood pressure under 120/80. High blood pressure also damages your artery walls.
• If you have diabetes, keep it under control. High blood sugar levels lead to:
• Higher LDL and triglyceride levels
• Denser LDL fat particles, which are more likely to form deposits in your arteries

What if my cholesterol level is still too high?

If lifestyle changes aren't enough to keep your cholesterol in check, your doctor may prescribe cholesterol-lowering medications. These medications often act on the liver to lower the amount of cholesterol that your body makes.

Some common cholesterol-lowering medications (and their brand names) include:

• atorvastatin (Lipitor)
• fluvastatin (Lescol)
• lovastatin (Mevacor)
• pravastatin (Pravachol)
• simvastatin (Zocor)
• niacin (Nicobid)

You can't just rely on medication to lower your cholesterol. You need to play an active role in making good lifestyle choices. That's the best way to help keep your heart as healthy as possible.

1. Centers for Disease Control and Prevention, 2003.

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