High cholesterol

Definition

When someone has too much cholesterol in the blood, it is a condition called hypercholesterolemia or hyperlipidemia. It is simply known as high cholesterol.

Description

Cholesterol, a lipid, is a fatty substance that bonds with a protein, becoming a lipoprotein. It is made in the liver and is carried throughout the body via the bloodstream. Cholesterol helps create cell membranes and also helps make and maintain nerve cells. In addition, it aids in the production of the hormones estrogen and testosterone and assists digestion in the intestines.

There are two types of lipoproteins that can affect health. Low-density lipoproteins (LDLs) are thought to be bad because they contribute the deposition of fat on artery walls. These deposits can restrict blood flow or block it entirely, causing a heart attack or stroke . This condition is called atherosclerosis . In contrast, high-density lipoproteins (HDLs) clean cholesterol from the blood, returning it to the liver. HDLs DH can protect against coronary artery disease.

Triglycerides, also found in the blood, are fats that form when the body consumes extra calories from any food source. It does not matter whether the extra food is a fat, a protein, or a carbohydrate, the body, in its efficiency, converts that extra food into fat for storage. Triglycerides, therefore, become convenient storage packages. Some medical conditions, such as hypothyroidism, can produce high levels of

triglycerides, even if the body is at a proper weight and no extra calories are consumed.

Trouble begins when too much cholesterol accumulates in the blood. Fat deposits called plaques can form in the blood vessels. Like build up in plumping pipes, plaques can close arteries supplying oxygen and nutrients to cells. This can reduce oxygen to the brain and put the heart at risk. It also can cause high blood pressure . Sometimes, plaques can even block arteries so that the patient has a heart attack or stroke. In addition, part of a plaque may tear away becoming a blood clot and travel throughout the body, eventually blocking an artery. If that blockage occurs in the brain, the heart, or the lung, a heart attack, stroke, or even death may occur.

Risk factors

Managing high cholesterol often depends on other risk factors for coronary artery disease. Many of these factors are based on age and gender. If the patient is a man over 45 or has a father or brother who had coronary artery disease before age 55, his risk is increased. If the patient is a woman over 55, has a mother or sister with coronary artery disease before age 65, or has premature menopause , her risk is also increased. Smoking and diabetes raise risk because both damage the walls of the blood vessels, making them more prone to fatty deposits. Being inactive, being overweight, or having high blood pressure also contributes to risk.

Demographics

Nearly 107 million American adults have total cholesterol readings of 200 mg/dL or higher and 37.2 million have extremely high readings of 240 mg/dL or higher and are considered high risk. The risk of having this condition increases with age. The highest prevalence occurs in women between the ages of 65 and 74.

One in 500 people have an inherited disorder, which causes extremely elevated cholesterol levels that can reach over 300 mg/dL. That condition, called familial hypercholesterolemia, causes cholesterol-filled nodules to form on tendons in the lower extremities or on the eyelids.

Causes and symptoms

Causes

Though cholesterol is made in the liver, elevated levels of cholesterol in the blood are not necessarily a factor of overproduction. It is most commonly a factor of high consumption of foods containing cholesterol and fats, particularly saturated fats and trans fats. This intake of fats, combined with inactivity, is the main cause of high cholesterol. Some people, however, do inherit a liver that overproduces cholesterol or they inherit an inability to process cholesterol properly. Others have diseases that elevate cholesterol in the blood, such as diabetes, hyperthyroidism, kidney disease, or liver disease.

Symptoms

Like high blood pressure, high cholesterol has no symptoms. It is only when coronary artery disease or a blood clot forms that symptoms occur. This can range from a severe pain in the leg caused by a blocked or narrowed artery to a heart attack or stroke.

Diagnosis

Though a doctor may take a detailed medical history and do a physical exam, the only definitive way to diagnose high cholesterol is by a blood test. The results of that test, combined with other risk factors that the patient may have, will determine the treatment regime. Having diabetes or having had a heart attack puts the patient at very high risk. However, a patient with two or more risks factors, including low HDLs, is also at very high risk.

The blood test, called a lipid panel or lipid profile, measures the total amount of cholesterol in the blood, LDL cholesterol, HDL cholesterol, and triglycerides. The patient does not eat or drink anything for nine to 12 hours before the test. Then, a single blood draw is done.

Cholesterol is measured in milligrams (mg) of cholesterol per deciliter (dL) of blood. In 2004, the National Cholesterol Education Program (NCEP) released guidelines that urged physicians to consider the patient's risk of having heart disease when making a diagnosis of high cholesterol and when drafting a treatment plan, instead of relying on the results of the lipid panel alone. In 2006, the NCEP issued new cholesterol guidelines to further help doctors refine their diagnoses. Treatment is based on the patient's medical history, other risk factors for cardiovascular disease, and on LDL levels. Though a person may have high HDL readings, if the LDL measures are high, then treatment should be based on lowering the LDL level.

Total cholesterol levels

Desirable total cholesterol levels for an otherwise healthy adult should be below 200 mg/dL. If the levels are between 200 and 239 mg/dL, the level is considered borderline high, whereas a level of 240 mg/dL or above is considered very high.

QUESTIONS TO ASK YOUR DOCTOR

• How often should I have my cholesterol checked?
• What tests will be done?
• What are my risk factors for coronary artery disease?
• What dietary changes can I make?
• How much exercise should I get?
• What kind of medication are you giving me?
• How does this medication work to lower my cholesterol?
• What are the side effects of this medication?
• Is there a generic version of the medication?
• How do I take this medication?
• How often do I return to see the doctor?

LDL levels

Normally, the optimal level for LDLs is between 100 and 129 mg/dL, with borderline high readings of 130–159 mg/dL, high readings of 160–189 mg/dL, and very high readings of 190 mg/dL and higher. For people at moderate risk for heart disease, the LDL levels should be below 100 mg/dL. For those with very high risk, the levels should be under 70 mg/dL.

HDL levels

The best measure of HDL cholesterol should be at 60 mg/dL or higher. A good reading is between 40 and 59 mg/dL. Anything below 40 mg/dL puts the patient at risk for coronary heart disease.

Triglyceride levels

The most desirable triglyceride level is below 150 mg/dL. Borderline high readings range from 150 to 199 mg/dL. High levels are between 200 and 499 mg/dL, and a measure of 500 mg/dL or above is dangerously high.

Treatment

The first stage of treatment many physicians choose is making lifestyle changes. This is crucial for people who have borderline high readings. If dietary changes are not sufficiently effective in reducing total cholesterol and LDL numbers, the doctor may prescribe medications. If the patient also has other risk factors for coronary artery disease, medications may be prescribed as soon as the diagnosis is made. Sometimes, medications are used in combination with lifestyle changes.

Lifestyle changes

Two lifestyle changes that doctors recommend are getting more exercise and eating a diet low in fat, especially trans fats and saturated fats. Doctors also encourage patients with high cholesterol to maintain a healthy weight. For many patients, this may mean losing weight. Exercise not only can help the patient lose weight, but it lowers total cholesterol and LDLs and raises HDLs.

Medications

There are five types of medications used to lower cholesterol. Each type of drug works differently on cholesterol production and each has different side effects.

statins These medications are also called HMG-CoA reductase inhibitors because they block HMG-CoA reductase, a substance that is necessary in cholesterol production. This causes the liver to make less cholesterol, and draw it from the blood that it filters. Statins can also help the body reabsorb cholesterol from accumulations on the artery walls, often reversing coronary artery disease.

Statins are the most commonly prescribed drugs for high cholesterol. They include atorvastatin (Lipitor), fluvastin (Lescol), lovastatin (Altoprev, Mevacor), pravastatin ((Pravachol), rosuvastatin (Crestor), and simvastatin (Zocor). This class of drugs is usually well tolerated, but side effects include serious muscle fatigue and liver complications. In order to monitor liver function, a blood test is done yearly when cholesterol levels are measured.

bile acid-binding resins The liver uses cholesterol to make bile acids, which are used to digest food. Medications using bile acid-binding resins bind cholesterol to bile acids, forcing the liver to use excess cholesterol to make bile acids. This helps remove cholesterol from the blood. These drugs include cholestyramine (Prevalite, Questran), colesevelam (WelChol), and colestipol (Colestid). They are not prescribed alone but in combination with a statin.

cholesterol absorption inhibitors Ezetimibe (Zetia) and its companion, Vytorin, which combines Zetia and the statin Zorcor, had the promise of being a new way to reduce cholesterol and, therefore, reducing the risk of coronary artery disease. This class of drugs restricts the absorption of cholesterol from food in the small intestine. In 2007, the New England Journal of Medicine published the results of a study completed two years previously that found that even though Vytorin reduced three risk factors for heart disease (LDLs, triglycerides, and CRP, a measure of artery inflammation), the drug had failed to improve heart disease prevalence. The study reinforced the use of statins as the most effective and affordable drugs to prevent heart disease.

WHEN TO SEEK MEDICAL ATTENTION

Cholesterol should be checked every five years if normal levels are found. If the patient is on high cholesterol medication, a blood test to check liver function should be done every year once therapeutic dosage is achieved and cholesterol levels are lowered. The doctor may recommend testing more frequently as cholesterol levels are being reduced.

niacin Niacin (Niaspan) and fibrates are used to reduce triglycerides and raise HDLs. Niacin limits the liver's ability to produce LDLs and very low density lipoproteins (VLDLs). Niaspan is high dosage niacin and differs from the dietary supplement. Niaspan should only be used under a doctor's supervision. Some patients experience flushing when they take Niaspan. This can usually be avoided by taking an aspirin several minutes before taking Niaspan.

fibrates Fibrates work like Niaspan, but they also speed up the removal of triglycerides from the blood. These drugs include clofibrate (Abitrate), fenofibrate (Tricor), and gemfibrozil (Lopid).

Alternative treatments

Herbal dietary supplements have not been proven to reduce cholesterol, though anecdotal reports have found a few of them may be helpful. These include barley, artichoke extract, oat bran, garlic extract, and blond psyllium (found in products such as Metamucil). Sitostanol and beta-sitosterol have been used as oral supplements and as added ingredients in some margarines such as Benecol and Take Control. Any dietary supplement should be used only with a doctor's approval because of the risk of interaction with other medications.

Nutrition/Dietetic concerns

Often called the Therapeutic Lifestyle Changes diet or the TLC diet, this low-cholesterol and low-fat eating plan is often prescribed. It limits foods containing cholesterol and fats. Patients are told to avoid processed foods, especially fast foods that are deep fried. They should also choose lower fat dairy products, trim visible fat from meats (even lean meats), and cook with olive, canola, or peanut oil. In addition, by limiting sugar and alcohol and trimming overall calories, older adults with high cholesterol and triglyceride readings can reduce those numbers as well as the risk for serious heart disease and strokes.

Interestingly, the NCEP diet recommendations do not totally eliminate saturated fat since some may even be helpful, but should be limited to only 7 percent of total calories in the diet. Monounsaturated fats should compose 20 percent of all food calories and polyunsaturated fat only 10 percent. Cholesterol should be limited to 200 milligrams a day. Foods that contain cholesterol are eggs, red meats, liver, shrimp, and dairy products. Eating high fiber food such as fruit, whole grains, oatmeal, and raw vegetables can also help lower cholesterol and triglyceride levels. The NCEP recommends consuming 25 grams of fiber every day.

The NCEP also advises limiting meats and other proteins. They should comprise only 15 percent of all calories. Carbohydrates , therefore, should form the foundation for the healthy diet, composing half of all calories.

Some patients may seek advice from a dietician or nutritionist to make sure they are finding the correct foods for their diets.

Prognosis

Though cholesterol levels can be significantly reduced within six weeks of a change to a healthy diet and adopting an exercise program, for many, the struggle to lower their cholesterol and triglyceride numbers becomes a long-term challenge. Diet and exercise changes need to be permanent lifestyle alterations.

Prevention

For many people, high cholesterol is preventable. Exercising regularly, eating a healthy diet, and not smoking can keep cholesterol levels low. For others, it is a matter of heredity and cannot be avoided. However, even in those patients, healthy lifestyle choices and medications can greatly reduce the risks of coronary artery disease and other heart complications.

KEY TERMS

Atherosclerosis —A condition that occurs when plaque builds up along the walls of the arteries, causing them to become still and hardened; also called hardening of the arteries.

Cholesterol —A fatty substance called a lipid that is essential to cell life.

Lipoprotein —A lipid that bonds with a protein

Saturated fat —A fat that comes from an animal source that contributes to the formation of cholesterol in the blood.

Polyunsaturated fat —A fat consisting of more than one fatty acid that does not come from animal source and does not contribute to high cholesterol.

Monounsaturated fat —A non-animal fat that contains one fatty acid.

Resources

PERIODICALS

“Ask the doctor: Which is more important, high bad cholesterol or high good cholesterol?.” Staying healthy from the Faculty of Harvard Medical School. (August 21, 2006): NA

Freeman, Mason. “Drug treatments for high cholesterol.” What To Do about High Cholesterol (Harvard Special Health Report). (August 2006): 32–41

“High cholesterol (hypercholesterolemia).” Clincal Reference Systems. (May 31, 2007): NA

“High cholesterol: Lowering your risk and your druck bill.” Harvard Health Commentaries. (August 21, 2006): NA

Marchione, Marilynn. “Doctors wary after cholesterol drug flop.” Associated Press. (March 30, 2008): page

OTHER

“High blood cholesterol.” http://www.mayoclinic.com/health/irritable-bowel-syndrome/DS00178.

NIH Senior Health. http://www.nihseniorhealth.gov.

ORGANIZATIONS

American Heart Association National Center, 7272 Greenville Avenue, Dallas, Texas, 75231-4596, 800-242-8721, www.americanheart.org.

National Heart, Lung, and Blood Institute (NHLBI), PO Box 30105, Bethesda, Maryland, 20824-0105, 301-592 73, www.nhlbi.nih.gov.

National Institute on Aging (NIA), 31 Center Drive, MSC 2292, Building 31, Room 5C27, Bethesda, Maryland, 20892, 301-496-1752, 301-496-1072, www.nia.nih.gov.

Janie F. Franz