Pediatric Dyslipidemia

Cardiovascular disease is the leading cause of mortality in the United States and many other countries worldwide. One in three deaths worldwide occurs from cardiovascular events. It is now well known that atherosclerosis begins in childhood. Dyslipidemia, when recognized and treated in childhood, can reduce the risk of premature adverse cardiovascular events and mortality. This is especially relevant in the current age with the rising rates of obesity.  Dyslipidemias are defined as a group of lipoprotein abnormalities that can result in any of the following lipid abnormalities. Elevated total cholesterol (TC). Elevated low-density lipoprotein-cholesterol (LDL-C). Elevated non-high-density lipoprotein cholesterol (HDL-C). Elevated triglycerides (TG). Decreased HDL-C. A lipid panel should ideally be done after fasting for 8-9 hours. A complete lipid panel includes direct measurement of TC, HDL-C, and TG. LDL-C is calculated in the lipid profile using the Friedewald formula (LDL-C = Total cholesterol - (Triglyceride / 5) - HDL-C).  The Friedewald formula can only be used if the TG levels are lower than 400 mg/dl. If the TG levels are higher than 400 mg/dl, LDL-C must be measured directly (Direct LDL-C). Non-HDL-C is calculated by subtracting HDL cholesterol from total cholesterol and includes all atherogenic particles, including LDL-C, VLDL-C, IDL-C, and lipoprotein(a). A fasting sample is ideal because food intake can alter triglyceride levels; the differences between fasting and nonfasting TC and HDL-C are not clinically significant.  An abnormal test should be followed by a repeat lipid profile done two weeks to 3 months later for confirmation.  Current guidelines recommend universal screening in the pediatric age group between ages 9 and 11 years and between 17 and 21 years, as per National Lipid Association and the National Heart, Lung, and Blood Institute (NHLBI) Expert Panel.  During puberty, LDL cholesterol levels may drop physiologically. Hence screening is recommended in this age group. Universal screening is important because family history may not be reliable, and early diagnosis can make a substantial difference. For example, although the risk of premature cardiovascular disease is 20 times higher in familial hypercholesterolemia, only 20% of familial hypercholesterolemia is diagnosed.   This is done for children with risk factors. Screening is recommended in younger children (over two years of age) in the presence of the following: family history of hypercholesteremia or premature coronary heart disease (myocardial infarction, coronary bypass surgery in men under 55 years and women under 65 years), or presence of risk factors such as obesity, diabetes, and hypertension. Lipid values in children vary by age and gender. As per the Expert panel on integrated guidelines for cardiovascular health and risk reduction in children and adolescents, here is a table listing normal, acceptable, and borderline values for the various sub-components of a lipid panel.  These values are consistent with cut-off guidelines by the American Heart Association and the American Academy of Pediatrics.