Cholesterol Diagnosis

  • Diagnosis

    Cholesterol is a fatty substance in the body that is used for many different purposes. It is manufactured by the body and also found in animal products, such as red meat and dairy products.

    Cholesterol is found in all parts of the human body. It plays an essential role in the production of hormones and other functions. Cholesterol is a key element in the cell membranes of mammals, and it aids in the production of adrenal and sex hormones and vitamin D. Cholesterol comes from the foods you eat, and is also produced by the liver.

    Doctors divide cholesterol into high density lipids (HDL), low density lipids (LDL), and triglycerides. Having too much LDL cholesterol in your blood is a risk factor for heart disease and stroke. Having high levels of triglycerides can also put you at risk of heart disease if you have diabetes. Very high levels of triglycerides can increase your risk of pancreatitis. Figure 01. The excess buildup of cholesterol in the blood is referred to as hypercholesterolemia, which simply means "high cholesterol." Atherosclerosis, or hardening of the arteries, occurs when cholesterol collects and hardens on the walls of the arteries, causing them to thicken and narrow. This narrowing prevents adequate blood supply from reaching the heart. Both diet and medication can help control high cholesterol levels, thereby reducing risk factors for heart disease. Elevation of cholesterol and/or triglycerides is also referred to as hyperlipidemia.

    Click to enlarge: A normal artery and an artery with cholesterol buildup (plaque)

    Figure 01. A normal artery and an artery with cholesterol buildup (plaque)

    Because fat is not soluble in water, the cholesterol needs a carrier to travel through the blood, a liquid that primarily consists of water. Cholesterol must be transported on fat carrying proteins known as lipoproteins.

    There are two different kinds of lipoproteins that you may be aware of that have direct relation to the risk of heart disease: Low density lipoprotein (LDL or "bad cholesterol") and high density lipoprotein (HDL or "good cholesterol"). Both vary in the amount of lipid they carry. Low-density lipoproteins (LDL) often referred to as the "bad cholesterol" carrier, carry about 60% of the cholesterol in the bloodstream. High levels of LDLs can ultimately lead to heart disease because they are the major cause of buildup and blockage in the arteries. At every stage of atherosclerosis (plaque formation in the arteries that can lead to heart attack), high LDL cholesterol worsens the condition. On the other hand, high-density lipoprotein (HDL) may prevent oxidation of LDL and helps prevent the LDLs from sticking to the walls of the arteries and thus prevents the buildup of cholesterol plaque. The lipoprotein carries cholesterol away from the arteries to the liver and adrenal glands. Thus, the goal is to keep the LDL cholesterol low and the HDL cholesterol high.

    Elevated cholesterol may be due to genetics. In some individuals, elevated LDL cholesterol levels are due to heredity. These genetic disorders are referred to as familial hypercholesterolemia, familial combined hyperlipidemia, familial defective apolipoprotein B, and polygenic hypercholesterolemia. These disorders are linked to a defect in the way your body handles LDL cholesterol, which leads to high LDL levels.

    A diet high in animal fat diet is a major cause of elevated blood cholesterol. Dietary cholesterol plays a large part in raising blood cholesterol levels. This is especially true in North America and Europe, where the diet is heavily based on animal foods, such as meat, egg yolks, poultry, seafood, and milk products. Almost all food from plants, however, such as fruits, vegetables, vegetable oils, grains, cereals, and nuts, do not contain cholesterol. Individual persons, however, vary considerably in their response to a diet high in cholesterol. Some respond with marked increases in total cholesterol and LDL-cholesterol. Others do not respond significantly at all. Currently, we do not have a way to determine the underlying cause of such responses other than observing a trial on a low cholesterol, low saturated fat diet. Very high intakes of dietary cholesterol may be harmful even though blood cholesterol levels do not vary much.

    Other factors can cause you to develop high cholesterol. These factors include having diabetes, being a smoker, being obese, and the use of certain medications. People who can modify or change these risk factors can sometimes lower their cholesterol levels.

    You may have elevated cholesterol without having any symptoms. A person with high cholesterol levels may not experience any symptoms associated with the disorder. Cholesterol buildup, which narrows the arteries that carry blood to essential organs such as the heart and brain, takes place slowly, with no symptoms. Because there are usually no warning signs, it is extremely important to undergo routine blood tests for cholesterol and to take necessary steps to bring high levels down to a healthy range. If not adequately lowered, these elevated cholesterol levels could lead to heart disease and stroke.

    Age, gender, high blood pressure (hypertension), family history of heart attack, and having gone through menopause are other risk factors for having high cholesterol Figure 02. Older people are more susceptible to having high cholesterol, high blood pressure, and heart attacks. Men tend to have more trouble with high cholesterol and heart disease at earlier ages. However, after about the age of sixty, the incidence rate is the same.

    If high cholesterol is in your family, you are more susceptible as well. Women who have gone through menopause are believed to be at greater risk for high cholesterol because they have lower levels of the hormone estrogen in the bloodstream. Estrogen is thought to be a protective agent against heart disease in general and high cholesterol, though studies show that taking estrogen pills after menopause can increase the risk of heart disease in women.

    Click to enlarge: Blood pressure chart

    Figure 02. Blood pressure chart

    Being overweight, leading a sedentary lifestyle, eating a diet rich in saturated fats, and smoking can put you at great risk for having high cholesterol. Excess body weight can contribute to high cholesterol and most importantly to high triglycerides and low HDL cholesterol (HDLc). Individuals with a waist circumference of more than 40 inches if male and 35 inches if female and accompanying high triglycerides are found to have an increased risk of heart attack. Saturated fat, and cholesterol, found in animal products, can raise your blood cholesterol levels. Saturated fat raises these levels more than any other single dietary ingredient. Current smoking also put you at risk for heart disease several ways. Smoking lowers HDL cholesterol and smokers are more likely to have cholesterol rich plaques rupture and have heart attacks. Not getting enough exercise also contributes to your risk of heart attack. Those who exercise in regular fashion have higher HDLc, lower triglycerides, and are less likely to develop diabetes.

    While anyone can develop high cholesterol, certain drugs can put you at higher risk. In addition to heredity and drugs, certain diseases may also contribute to your risk of heart attack by raising levels of cholesterol and/or triglycerides. These factors include low thyroid gland activity (hypothyroidism), some forms of diabetes, and certain kidney and liver disorders. Drugs that alter lipid levels include drugs for high blood pressure like beta blockers and diuretics, endocrine drugs like birth control pills, female hormones and steroids (prednisone) and dermatologic drugs like retinoic acid (for acne). Certain drugs used to treat HIV can also increase cholesterol. Some actions are favorable (estrogens lower LDL) but some are not. This needs to be discussed with your doctor. If an essential drug increases your cholesterol, your doctor can prescribe a drug that lower your cholesterol.

    The National Cholesterol Education Program guidelines state tha all adults age 20 years and older should have their blood cholesterol checked every five years. They recommend that you fast overnight before you have a full cholesterol panel checked. If you have are diagnosed with high cholesterol, you will be checked more frequently. .

    The most common measurement of blood cholesterol is called total blood cholesterol Table 01. Total cholesterol is measured in milligrams per deciliter of blood (mg/dL), and it is the number given in your test results. Another important measurement is the "good" HDL cholesterol level.

    If you have high blood cholesterol (total cholesterol 240 mg/dL or higher) or low HDL cholesterol (HDL cholesterol less than 35 mg/dL), you are considered at higher risk for heart disease.

    Because "bad" LDL cholesterol is a better predictor of heart disease risk than total blood cholesterol, you may need to have your LDL cholesterol checked. This blood test requires fasting before the test, meaning you cannot eat or drink for 12 hours beforehand. The following table describes the categories of LDL cholesterol, which apply to adults age 20 years and older who have no other health problems.

    Your physician can interpret your results and tell you when to have your cholesterol levels tested again. If your cholesterol level is high or borderline-high, a treatment program may be necessary. Your doctor may also request a test called a lipoprotein analysis if you have additional risk factors. This involves measuring your levels of total cholesterol, total triglyceride, and HDL cholesterol after you have fasted.

    Table 1.   Blood Cholesterol Measurements

    Total cholesterol What it means
    Less than 200 mg/dL Desirable blood cholesterol
    200 to 239 mg/dL Borderline-high cholesterol
    240 mg/dL and higher High blood cholesterol
    HDL cholesterol
    Less than 35 mg/dL Low HDL cholesterol
    LDL Cholesterol Level Categories
    Less than 130 mg/dL Desirable
    130 to 159 mg/dL Borderline-High Risk
    160 mg/dL and above High Risk

    Source:"Facts about Blood Cholesterol," U.S. National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication No. 96-2696

    Doctors aim for lower LDL levels for patients who already have risk factors for heart disease. If you have one of the following risk factors, your LDL goal is less than 130 mg/dL: smoking, high blood pressure, low HDL or a family history of early heart disease. If you have 2 or more of the risk factors, or you have diabetes, severe blockages in the carotid arteries leading to your neck, peripheral artery disese, or a history of abdominal aneurysm, then your LDL goal would be less than 100 mg/dL. If you already have heart disease, your doctor will try to lower your cholesterol to 80 mg/dL or less. In addition to these cholesterol tests, you should undergo a complete health history, a physical examination, and have standard laboratory tests performed. The exam, history, and lab tests all help your doctor determine whether the cause of your elevated total cholesterol level is due to hereditary factors, another disease, or drugs you are taking. This information will help him or her to plan a program to improve your cholesterol levels.

    Prevention is essential in reducing your risk of heart attack and modifying your diet is a great first step to lowering your risk. Learn about which fats to avoid and which to include Table 02. Because high blood cholesterol increases your risk of heart attack due to heart disease, it is important to have your total blood cholesterol (cholesterol panel) tested on a routine basis and to take steps to prevent elevated cholesterol levels. Even if your blood cholesterol levels are desirable, it is wise to make healthy choices to maintain a satisfactory balance.

    Table 2.   Types of Fat

    Total Fat The sum of saturated, monounsaturated, and polyunsaturated fats that are present in varying combinations of foods.
    Saturated Fat This kind of fat is present in skin (chicken, for example), whole-milk dairy products, lard, and some vegetable oils, including coconut and palm oils. Saturated fat raises blood cholesterol more than any other type of fat or food.
    Unsaturated Fat This type of fat usually is in liquid form at refrigerator temperature. Monounsaturated fat and polyunsaturated fat are two types of unsaturated fat. The use of monounsaturated and polyunsaturated fats instead of saturated fat can help to lower blood cholesterol levels.
    Monounsaturated Fat This unsaturated fat is present in greatest amount in food from plants. Examples of monounsaturated fats are olive oil and canola oil.
    Polyunsaturated fat This is an unsaturated fat found predominantly in food from plants. Examples include safflower, sunflower, corn, and soybean oils.

    This information was adapted from "So You Have High Cholesterol," U.S. National Institutes of Health National Heart, Lung, and Blood Institute, NIH Publication No. 93-2922.

    You can often lower your cholesterol levels though such simple means as a low-fat diet and exercise Table 03. The goal to lower your cholesterol is achievable. A healthy diet, physical exercise, and, if necessary, weight loss are key steps you can take to lower your cholesterol levels, which ultimately lowers your risk for heart disease. The National Cholesterol Education Program (NCEP) recommends that all healthy individuals two years of age and older start eating foods lower in saturated fat and dietary cholesterol to lower blood cholesterol levels. For anyone over the age of two years, less than 10% of calories should come from saturated fat, 30% of calories or less should come from total fat, and less than 300 mg a day of dietary cholesterol should be eaten.

    If you are unable to lower your blood cholesterol levels on this diet, you may need a special diet prescribed by your doctor. Always be sure to check with your doctor before placing your child on a low fat or other special diet.

    Table 3.  Suggestions for Lowering or Maintaining Blood Cholesterol Levels

    Select foods low in total fat and low in saturated fat Fruits, vegetables, and whole grains are low in total fat and high in starch and fiber. Substitute unsaturated fat (polyunsaturated or monosaturated) for saturated fat.Because fat is a plentiful source of calories, eating foods low in fat enables you to consume fewer calories, and this will help you lose weight.
    Select foods high in starch and fiber High starch/high fiber foods are lower in calories than foods high in fat and also serve as good sources of essential vitamins and minerals. Foods high in starch and fiber include breads, cereals, pasta, grains, fruits, and vegetables.
    Select foods low in dietary cholesterol Dietary cholesterol comes from animal food products, such as egg yolks and organ meats, such as liver. Egg whites and food from plants do not contain dietary cholesterol.
    Get some physical exercise Physical activity helps improve blood cholesterol levels by lowering LDL cholesterol and raising HDL cholesterol. Exercise also helps in weight loss, lowering blood pressure, reducing stress, and improving the fitness of heart and blood vessels.
    Maintain or lose weight as appropriate Overweight individuals frequently have higher blood cholesterol levels than those with healthy weight.Cutting back on dietary fat will reduce calorie intake. Avoid "crash diets" that are very low in calories, however, because they can be harmful to your overall good health.

    Source:The information in this table was adapted from "Facts about Blood Cholesterol, U.S. National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication No. 96-2696."

  • Prevention and Screening

    Prevention is essential in reducing your risk of heart attack and modifying your diet is a great first step to lowering your risk. Learn about which fats to avoid and which to include Table 02. Because high blood cholesterol increases your risk of heart attack due to heart disease, it is important to have your total blood cholesterol (cholesterol panel) tested on a routine basis and to take steps to prevent elevated cholesterol levels. Even if your blood cholesterol levels are desirable, it is wise to make healthy choices to maintain a satisfactory balance.

    Table 2.   Types of Fat

    Total Fat The sum of saturated, monounsaturated, and polyunsaturated fats that are present in varying combinations of foods.
    Saturated Fat This kind of fat is present in skin (chicken, for example), whole-milk dairy products, lard, and some vegetable oils, including coconut and palm oils. Saturated fat raises blood cholesterol more than any other type of fat or food.
    Unsaturated Fat This type of fat usually is in liquid form at refrigerator temperature. Monounsaturated fat and polyunsaturated fat are two types of unsaturated fat. The use of monounsaturated and polyunsaturated fats instead of saturated fat can help to lower blood cholesterol levels.
    Monounsaturated Fat This unsaturated fat is present in greatest amount in food from plants. Examples of monounsaturated fats are olive oil and canola oil.
    Polyunsaturated fat This is an unsaturated fat found predominantly in food from plants. Examples include safflower, sunflower, corn, and soybean oils.

    This information was adapted from "So You Have High Cholesterol," U.S. National Institutes of Health National Heart, Lung, and Blood Institute, NIH Publication No. 93-2922.

    You can often lower your cholesterol levels though such simple means as a low-fat diet and exercise Table 03. The goal to lower your cholesterol is achievable. A healthy diet, physical exercise, and, if necessary, weight loss are key steps you can take to lower your cholesterol levels, which ultimately lowers your risk for heart disease. The National Cholesterol Education Program (NCEP) recommends that all healthy individuals two years of age and older start eating foods lower in saturated fat and dietary cholesterol to lower blood cholesterol levels. For anyone over the age of two years, less than 10% of calories should come from saturated fat, 30% of calories or less should come from total fat, and less than 300 mg a day of dietary cholesterol should be eaten.

    If you are unable to lower your blood cholesterol levels on this diet, you may need a special diet prescribed by your doctor. Always be sure to check with your doctor before placing your child on a low fat or other special diet.

    Table 3.  Suggestions for Lowering or Maintaining Blood Cholesterol Levels

    Select foods low in total fat and low in saturated fat Fruits, vegetables, and whole grains are low in total fat and high in starch and fiber. Substitute unsaturated fat (polyunsaturated or monosaturated) for saturated fat.Because fat is a plentiful source of calories, eating foods low in fat enables you to consume fewer calories, and this will help you lose weight.
    Select foods high in starch and fiber High starch/high fiber foods are lower in calories than foods high in fat and also serve as good sources of essential vitamins and minerals. Foods high in starch and fiber include breads, cereals, pasta, grains, fruits, and vegetables.
    Select foods low in dietary cholesterol Dietary cholesterol comes from animal food products, such as egg yolks and organ meats, such as liver. Egg whites and food from plants do not contain dietary cholesterol.
    Get some physical exercise Physical activity helps improve blood cholesterol levels by lowering LDL cholesterol and raising HDL cholesterol. Exercise also helps in weight loss, lowering blood pressure, reducing stress, and improving the fitness of heart and blood vessels.
    Maintain or lose weight as appropriate Overweight individuals frequently have higher blood cholesterol levels than those with healthy weight.Cutting back on dietary fat will reduce calorie intake. Avoid "crash diets" that are very low in calories, however, because they can be harmful to your overall good health.

    Source:The information in this table was adapted from "Facts about Blood Cholesterol, U.S. National Institutes of Health, National Heart, Lung, and Blood Institute, NIH Publication No. 96-2696."

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