Cholesterol is a fat-like, waxy substance that can be found in all parts of the body. It aids in the production of cell membranes, some hormones and vitamin D. The cholesterol in blood comes from two sources: the foods your child eats and his or her liver. However, your child’s liver can make all of the cholesterol your child’s body needs.

Cholesterol and other fats are transported through the blood stream in the form of round particles called lipoproteins. The two most commonly known lipoproteins are low-density lipoproteins (LDL) and high-density lipoproteins (HDL).

A lipid screening consists of a blood test that provides a child’s health care team with an overall look at the fats in the blood. In the past, doctors felt that children and adolescents were at little risk for developing high cholesterol levels and other risk factors for heart disease until later in life. However, we now know that children and adolescents are at risk for having high blood cholesterol levels as a result of one or more of the following:

• Sedentary lifestyles (playing video games, watching TV, not participating in vigorous exercise)
• High-fat or high-sugar "junk food" diets
• Obesity
• Family history of high cholesterol levels.

A full lipid profile shows the actual levels of each type of fat in the blood, such as LDL, HDL, triglycerides and total cholesterol. The child's doctor will compare the child’s results with normal values after considering the child’s age and the number of risk factors present.

Children and adolescents with high cholesterol are at higher risk for developing heart disease as adults. Keeping blood cholesterol levels in the normal range throughout one's lifetime reduces the likelihood of developing heart and blood vessel diseases, such as coronary artery disease (blockages in the arteries that supply blood to your heart) and high blood pressure.

This type of cholesterol is commonly called "bad" cholesterol. It can contribute to the formation of plaque build-up in the arteries, known as atherosclerosis. People commonly refer to atherosclerosis as "blockages in my heart."

LDL levels should be low. To help lower LDL levels, children and adolescents should:

• Avoid foods high in saturated and trans fat, dietary cholesterol and excess calories in general
• Increase exercise
• Maintain a healthy weight.

This type of cholesterol is known as "good" cholesterol, and is a type of fat in the blood that helps to remove cholesterol from the blood, preventing the fatty build up and formation of plaque in your blood vessels. HDL should be as high as possible. It is often possible to raise HDL by avoiding saturates in foods and decreasing body weight. Vigorous exercise for 60 minutes each day can also help to increase HDL.

Triglycerides are another class of fat found in the bloodstream. The bulk of an adolescent's body fat tissue is in the form of triglycerides.

The link between triglycerides and heart disease is under clinical investigation. However, many children and adolescents with high triglyceride levels also have other risk factors such as high LDL levels or low HDL levels.

Elevated triglyceride levels may be caused by medical conditions such as diabetes, hypothyroidism, kidney disease or liver disease. Dietary causes of elevated triglyceride levels in children and adolescents may include obesity and high intakes of fat and concentrated sweets. Alcohol can be a factor for teens who drink.

Blood cholesterol is very specific to each person. In general, cholesterol levels are categorized as follows:

* Adapted from PEDIATRICS Volume 128, Supplement 6, December 2011

If the results of a child's lipid tests are abnormal, the child's doctor will work closely with the child and his or her family to devise a treatment plan based on the factors most likely causing the child’s high cholesterol. Most children and adolescents will not need prescription medication. Often, a healthy diet, weight loss and increased physical activity are enough to return blood lipid levels to normal.

In some cases, the child may be referred to a cardiologist or to a specialty program like the Lipid Clinic at CHOC Children’s.