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 adolescents who have high cholesterol continue to have high cholesterol when they are adults. Children 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 children 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 children 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 children 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 children 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 children, 30 mg/dl in adults).

TESTING THE CHOLESTEROL LEVELS IN CHILDREN

The American Academy of Pediatrics and the American Heart Association agree that all children who are at high risk for coronary heart disease should be screened soon after they are 2 years old.

The normal diet of children younger than 2 years is high in fat, and therefore high in cholesterol, because they are growing so fast. It is not appropriate to test children younger than 2 years.

A child 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. Over half of the children who have high cholesterol levels are found by testing children with these high risk factors.

Doctors do not agree on when to check the cholesterol levels of children who are not high risk. The main reason for testing everyone is to identify all children with high cholesterol. Eating and exercise habits that lower cholesterol levels need to be started early. The main arguments against testing all children are that it is costly, high cholesterol levels do not persist into adulthood half the time, and healthy diets can be started for all children without knowing their cholesterol levels. If a doctor or clinic does check the cholesterol levels of all children, they usually check children between 2 and 5 years old, often when they start kindergarten.

RETESTING CHILDREN WITH HIGH CHOLESTEROL LEVELS

If your child's cholesterol is borderline high or high, it will be checked again 1 to 2 weeks after the first test. Cholesterol levels do vary somewhat day to day, so it is important to confirm that the cholesterol is high.

Children 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. Treatment will start and the level of cholesterol will be checked again in about 2 to 4 months.

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

Lipid panels are not done for all children because they cost much more than the total cholesterol test. In addition, the lipid panel requires blood drawn from a vein. This can be a more difficult procedure for a child than pricking a finger.

RETESTING CHILDREN AND ADULTS WITH NORMAL CHOLESTEROL LEVELS

Children with total cholesterol below the 75th percentile do not need their cholesterol checked again until they become adolescents. Most physicians check the total cholesterol level of adults every 5 years as long as it remains in the normal range.

TESTING FAMILY MEMBERS

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

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