Clinical Reference Systems: Pediatric Advisor 10.0

THE IMPORTANCE OF LOW CHOLESTEROL

Everyone needs to have some cholesterol in their blood. Cholesterol is the normal way fat is carried in the bloodstream. However, people who have higher-than-normal levels of cholesterol have a greater risk of developing coronary heart disease (CHD). If they lower their cholesterol levels, they reduce their chances of having heart disease. A 1-percent decrease in blood cholesterol leads to a 2-percent decrease in the risk of CHD in adults. One major goal of preventive medicine is to lower high cholesterol levels to healthy levels.

The amount of cholesterol and saturated fats we eat affects the level of cholesterol in our blood. If we eat less cholesterol and saturated fat, we will have less cholesterol in our blood.

Many children and teenagers who have high cholesterol continue to have high cholesterol when they are adults. Teenagers who reduce their cholesterol levels with proper diet and exercise may have a better chance of having low cholesterol when they are adults.

TYPES OF CHOLESTEROL

Cholesterol has several components: high-density lipoproteins (HDL), low-density lipoproteins (LDL), and triglycerides. All of these components combined are called "total cholesterol." The HDL component is called the "good" cholesterol because it carries cholesterol away from the arteries to the liver. The liver helps the body get rid of cholesterol. LDL is called the "bad cholesterol." If you have too much LDL, the LDL leaves cholesterol on the inner walls of the arteries. As a result your arteries become clogged.

So, in addition to reducing total cholesterol levels, it is helpful to increase the HDL and decrease the LDL in the blood. A 1-percent rise in HDL may give adults a 3-percent decrease in the risk of coronary heart disease.

NORMAL AND ABNORMAL CHOLESTEROL LEVELS

Normal levels of total cholesterol in adolescents are between 120 and 170 mg/dl. After age 18, the levels considered to be normal rise about 1 point per year of age. A healthy level of total cholesterol is below the 75th percentile. For adolescents this means a cholesterol level below 170 mg/dl. (The level of cholesterol in adults should be below 200 mg/dl.) Levels between the 75th and 95th percentiles are considered to be borderline high. Levels above the 95th percentile (higher than 200 mg/dl in adolescents and 240 mg/dl in adults) are high and abnormal. In general, anyone who has a total cholesterol above the 75th percentile should try to lower it.

Levels of HDL, which we want to be high, should be above the 25th percentile (over 45 mg/dl in adolescents and over 40 mg/dl in adults). A borderline low value is between the 5th and 25th percentiles. A low or abnormal value is below the 5th percentile (less than 35 mg/dl in adolescents, 30 mg/dl in adults).

TESTING THE CHOLESTEROL LEVELS IN CHILDREN AND TEENAGERS

The American Academy of Pediatrics and the American Heart Association agree that all children and teenagers who are at high risk for coronary heart disease should be screened.

A person is at high risk of developing CHD as an adult if members of the family have had high blood cholesterol or early coronary heart disease. Family members include parents, grandparents, aunts, or uncles. A history of early coronary heart disease includes heart attack, angina, stroke, or bypass surgery that occurs in men less than 50 years old or women less than 60 years old. The information about grandparents is important because other relatives might not yet be old enough to have developed heart disease.

RETESTING TEENAGERS WITH HIGH CHOLESTEROL LEVELS

If your cholesterol is borderline high or high, it will be checked again one to two weeks after the first test. Cholesterol levels do vary somewhat day to day, so it is important to confirm that the cholesterol is high.

Teenagers with confirmed high total cholesterol (greater than the 95th percentile) will then have blood drawn for a lipid profile or panel. This test measures the levels of LDL, HDL, and triglycerides, as well as total cholesterol. Diet and exercise treatment will start and the level of cholesterol will be checked again in about 2 to 4 months.

If your total cholesterol level is borderline high (between the 75th and 95th percentiles), diet and exercise treatment can start without the lipid panel. Your total cholesterol will probably be rechecked every year.

Lipid panels are not done for all people because they cost much more than the total cholesterol test.

RETESTING TEENAGERS WITH NORMAL CHOLESTEROL LEVELS

Most physicians check the total cholesterol level of teenagers and adults every 5 years as long as it remains in the normal range.

TESTING FAMILY MEMBERS

If you have a high cholesterol (higher than 95th percentile), we recommend that everyone in your family have their total cholesterol checked. Very often the close relatives of teenagers with high cholesterol also have high cholesterol. Discovering that other family members have high cholesterol will encourage your entire family to start a healthier diet and exercise program.

For information on the treatment of high cholesterol, see Treating High Cholesterol Levels.