Pediatric Pathways

Assessment of Dyslipidemia in Children and Adolescents

After reading this article and answering the review questions the reader will be able to:

  1. Describe the importance of lipid screening for cardiovascular health in pediatric patients
  2. Order appropriate lipid screening tests and accurately interpret results
  3. Design a treatment plan for common patterns of pediatric dyslipidemia

Case

Michael, a 12-year-old male, is seen in your clinic because his mother wants her son “checked out” because heart disease runs in the family. Michael’s father recently underwent coronary artery bypass grafting at 33 years of age after developing severe chest pain. The father’s total cholesterol (TC) was greater than 500 mg/dL. Michael’s paternal grandmother died of a heart attack at the age of 52. Further review shows that Michael’s BMI has been tracking along the 95th percentile but has recently started to increase. His mother reports that she has been scared to let him exercise because he might have a heart attack. Michael reports his favorite foods are pizza, ice cream, and macaroni and cheese. He drinks 2% milk and refuses to eat vegetables, as he considers them to be “rabbit food.”

Michael’s fasting lipid profile shows a TC of 320 mg/dL, low-density lipoprotein (LDL) of 254 mg/dL, high-density lipoprotein (HDL) of 45 mg/dL, and triglycerides (TG) of 80 mg/dL.

Case Discussion

Familial Hypercholesterolemia

Disclosure: The FDA has approved atorvastatin, rosuvastatin, simvastatin, fluvastatin, lovastatin, ezetimibe, and colesevelam for the treatment of pediatric heterozygous and homozygous Familial Hypercholesterolemia in children 10 years of age and older. Pravastatin is FDA-approved for the same indications in children as young as 8 years old. Any other descriptions of medication use in this article are off-label uses.

This patient meets clinical diagnostic criteria for Familial Hypercholesterolemia (FH). FH is an autosomal dominant inherited disorder affecting 1 in 300 to 500 people, and is considered to be the most common life-threatening inherited condition. It is characterized by a markedly elevated LDL that is present from birth. Generally, HDL cholesterol and triglycerides are normal. FH should be suspected in a patient 20 years of age or younger if the untreated fasting LDL is ≥ 160 mg/dL or the total non-HDL cholesterol is ≥ 190 mg/dL, values that are substantially above the 95th percentile1.

The diagnosis is confirmed if the patient has a first-degree relative with premature atherosclerosis and an LDL > 200 mg/dL. Even in a screening population, if the LDL > 190, there is an 80% chance the child has FH.

The most common form of FH is caused by a loss-of-function mutation in the LDL receptor on hepatocytes, which is responsible for binding LDL and facilitating its metabolism in the liver3. The relative loss of receptor functionality is variable, hence, LDL levels and age of cardiovascular disease onset in patients with FH is also variable. Despite the variability, if untreated, approximately half of males and 25% of females will have a cardiovascular event before 50 years of age4.

In FH, lifestyle changes are critical to management but are almost never adequate to drop LDL levels back to normal. First-line therapy is a combination of lifestyle management with pharmacotherapy, usually a statin. Statins are FDA-approved for use in pediatric patients with FH as young as eight years of age. The goal of treatment is reduction of LDL below 130 mg/dL or a 50% reduction from baseline LDL (whichever is less aggressive), along with normalization of the rest of the lipid profile5. Rarely, pediatric patients will require additional cholesterol-lowering medications to reach goal levels.

In adults, the use of statin medications is remarkably effective at reducing cardiovascular mortality. The Simon Broome Familial Hyperlipidaemia Register Group showed impressive reductions in cardiovascular mortality (48% with primary prevention and 25% with secondary prevention), as well as a 33% reduction in all-cause mortality with statin use in their FH population6,7. In children with FH, use of statins leads to significant reductions in carotid intimal medial thickness, a well-validated surrogate marker for atherosclerotic burden in adults8. Even more importantly, a cohort of children with FH started on a statin between 8 to 18 years of age already have, only 10 years later, a lower cardiovascular event rate than their affected parents did at the same age9.

Despite the well understood, long-standing association with FH and ischemic heart disease10, FH is woefully underdiagnosed. In the US, less than 10% of patients with FH are appropriately diagnosed, and a smaller number still are appropriately treated2. Sensitivity and specificity of LDL cutoff values are much more predictive in pediatrics than they are with adult patients, and so a proper diagnosis in childhood can lead to appropriate diagnosis in other family members as well. The diagnosis of FH in one patient should prompt testing with a fasting lipid profile in all first-degree relatives.

Atherogenic Dyslipidemia

Overweight and obesity are well-established cardiovascular risk factors in adults, and pediatric obesity is linked to increased rates of dyslipidemia11. Unfortunately, the rising incidence of pediatric obesity in the United States is evident with approximately one-third of children classified as being either overweight or obese12.

Consequently, rates of pediatric dyslipidemia in the United States are rising.13 Previously, pediatric cholesterol guidelines have focused on identifying children with elevated LDL or with FH. However, the most common pediatric dyslipidemia is now atherogenic dyslipidemia, characterized by moderately to severely elevated TG, normal to mildly elevated LDL, and reduced HDL. Some estimates of incidence are as high as 1 in 100 children. It is most commonly associated with overweight or obesity, hypertension, fatty liver, and insulin resistance in the pediatric population. Table 1 compares features of atherogenic dyslipidemia and FH.

Table 1. Features of Atherogenic Dyslipidemia and Familial Hypercholesterolemia in the Pediatric Population

 

Atherogenic Dyslipidemia (AD)

Familial Hypercholesterolemia (FH)

Incidence

~1:100

1:300-500

Inheritance

Pattern

Polygenic

Monogenic (usually autosomal dominant)

Associated Conditions

Obesity, insulin resistance, hypertension

None

LDL Level

Normal

High

HDL Level

Low

Normal

TG Level

High

Normal

 

While the standard treatment of atherogenic dyslipidemia is fairly intuitive, its execution is often not. Lifestyle modification is first-line treatment, including regular physical activity and limited “screen time” as well as a diet low in saturated fat and cholesterol. Controlling intake of refined carbohydrates is also important, particularly in the setting of hypertriglyceridemia. Appropriate caloric intake is also important, particularly if the child is overweight or obese. Referral to a dietician experienced in treating children and families for medical nutrition therapy can be very helpful. Regular follow-up is important, and if dyslipidemias persist, then pharmacologic treatment may be recommended after careful consideration of a child’s family history and cardiovascular risk factors. The vast majority of pediatric patients with dyslipidemia will not require pharmacologic treatment, but patients with a LDL ≥ 190 mg/dL or TG ≥ 500 mg/dL almost certainly have a primary dyslipidemia14 and should be considered for referral to or consultation with a specialist with experience in treating pediatric dyslipidemias.15

Why universal screening?

In 2011, new pediatric lipid screening guidelines were published in the Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents: Summary Report.15 These guidelines recommend routine universal lipid screening with a non-fasting TC, HDL, and non-HDL cholesterol at ages 9 to 11 years old and again at 17 to 21 years old. Children and adolescents with higher risk medical conditions or concerning family histories can be screened as young as two years old or at the time the medical condition or concerning family history is diagnosed. For higher-risk children, a screen should be considered every five years thereafter.

This change in recommendation from selective to universal screening is important. The American Academy of Pediatrics (AAP) had revised their guidelines in 2008 in response to concerns regarding the epidemic of pediatric obesity and associated pediatric dyslipidemia. At that time, the recommendation was a fasting lipid profile for all children between 2 and 10 years old with identified family history or patient risk factors. These old recommendations indicated that a patient’s family history should prompt screening if a parent, grandparent, aunt, or uncle had high cholesterol or cardiovascular disease, or if the family history was unknown. Any patient who was overweight or obese, or had hypertension, tobacco use, or diabetes also met screening criteria.16 However, in order for this type of selective screening program to work, the patients that meet screening criteria needed to be properly identified. There are no clear standards for accurate family histories, and accurate measurement and interpretation of blood pressure in children and adolescents can be challenging.

Furthermore, in order for a selective screening program to work, the screening criteria also need to be sensitive enough to detect affected patients. Unfortunately, this is not the case with pediatric dyslipidemias. One study screened LDL cholesterol in over 20,000 fifth graders and demonstrated that 71% of children in their study population met screening criteria. Dyslipidemia requiring pharmacologic treatment, however, was more common among children who did not meet screening criteria than among those who did.17 Another study of 678 children found the AAP screening criteria were only 54 to 66% sensitive in identifying children with a dyslipidemia.18 Therefore, significant lipid disorders in pediatrics are commonly missed, even if there is full compliance with a selective approach.

Universal Screening Recommendations

According to the Expert Panel, the initial screening test can be total and HDL-cholesterol, which are accurate in the non-fasting state. The non-HDL cholesterol can then be calculated using the formula non-HDL = TC – HDL. Evidence supports that lipid levels drawn before puberty have a high correlation with adult levels and are stable, unlike levels drawn during puberty. During puberty, hormonal changes have been associated with a decrease in LDL cholesterol levels, with fluctuations in HDL and TG. The Dietary Intervention Study in Children (DISC) showed an average decrease in LDL cholesterol of 23.3 mg/dL in boys and 10.6mg/dL in girls in Tanner stage 4 or 5 compared to their LDL levels at Tanner stage 1.19 As a result of these normal decreases in LDL during puberty, the sensitivity and specificity of predicting adult LDL levels based on levels obtained during puberty is compromised and indiscriminate testing leads to a high false negative rate of detection. Despite decreases in LDL cholesterol levels during puberty, guidelines use the same reference ranges for lipid profiles in adolescents as they do in children. This is because the recommended thresholds for initiation of lifestyle or medical therapy are the same for children and adolescents. Universal screening is not recommended prior to age 9 due to the minimal data regarding medication use in children less than 8 years old. However, if new risk factors are identified between 10 and 17 years of age, then targeted screening with a fasting lipid profile may be appropriate. A brief summary of screening recommendations based on age is shown in Figure 1. Acceptable ranges for fasting and non-fasting lipid profiles for patients 0-19 years of age is shown in Figure 2.

Figure 1. Pediatric Lipid Screening Recommendations

Pediatric Pathways: Lipids screening chart

Adapted from: Kavey RW, Simons-Morton DG, and de Jesus JM, ed. Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents: Summary Report. Pediatrics 2011;128, Supplement 5.

Figure 2. Normal Non-fasting and Fasting Lipid Values for Children 0-19 Years

All values are mg/dL.

Pediatric Pathways: Normal lipid values chart

Adapted from: Kavey RW, Simons-Morton DG, and de Jesus JM, ed. Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents: Summary Report. Pediatrics 2011;128, Supplement 5.

Conclusion

Pediatric dyslipidemias are common and can be genetic or acquired. Two of the most common patterns of pediatric dyslipidemia are Familial Hypercholesterolemia, the prototype of inherited cardiovascular risk, and atherogenic dyslipidemia, which is generally seen in the setting of obesity and insulin resistance. Selective screening strategies, even with perfect implementation, have been shown to miss as many as half the children with a genetic or acquired dyslipidemia.

Cardiovascular disease is still the number one cause of death in the United States today. Effective intervention to address cardiovascular risk in childhood may represent our biggest opportunity to positively impact human health.

Referral Information

If you have a pediatric patient with a cholesterol disorder or you are concerned that a patient may have increased risk for early cardiovascular disease, the Pediatric Preventive Cardiology Clinic (PPCC) at the American Family Children’s Hospital evaluates patients from infancy through early adulthood. We also have PPCC outreach clinics at St. Elizabeth’s Hospital in Appleton, Wisconsin and at Aspirus Hospital in Wausau, Wisconsin. Please call 608-263-6420 to schedule an appointment, or visit our website at www.uwhealthkids.org/cholesterol.

Back to top

CME Questions

References

  1. Hopkins PN, Toth PP, Ballantyne CM, Rader DJ. Familial hypercholesterolemais: prevalence, genetics, diagnosis, and screening recommendations from the National Lipid Association Expert Panel on Familial Hypercholesterolemia. J Clin Lipidol. 2011;5(3 suppl):S9-S17.
  2. Familial Hypercholesteroaemia: Report of a second WHO Consultation. Geneva, 4 September 1998.
  3. Brown MS, Goldstein JL. A receptor-mediated pathway for cholesterol homeostasis. Science. 1986;232:34-47.
  4. Wiegman A, Rodenburg J, de Jongh S, Defesche JC, Bakker HD, Kastelein JJ, and Sijbrands EJG. Family history and cardiovascular risk in familial hypercholesterolemia: data in more than 1000 children. Circulation 2003;107:1473-1478.
  5. Goldberg AC, Hopkins PN, Toth PP, et al. Familial hypercholesterolemia: screening, diagnosis, and management of pediatric and adult patients. J Clin Lipidol 2011;5(3): 133-141.
  6. Versimissen J, Oosterveer DM, Yazzdanpanah M, et al. Efficacy of statins in familial hypercholesterolaemia: a long term cohort study. BMJ 2008;337:a2423.
  7. Neil A, Cooper J, Betteridge J, et al. Reductions in all-cause, cancer, and coronary mortality in statin-treated patients with heterozygous familial hypercholesteroleaemia: a prospective registry study. Eur Heart J 2008;29:2625-33.
  8. Rodenburg J, Vissers MN, Wiegman A, et al. Statin treatment in children with familial hypercholesterolemia: the younger the better. Circulation 2007;116:664-668.
  9. Braamskamp MJ, Kusters DM, Avis HJ, Wijburg FA, Kastelein JJ, Wiegman A, and Hutten BA. Patients with familial hypercholesterolemia who initiated statin treatment in childhood are at lower risk for CHD than their affected parents. Circulation 2013;128:A17837.
  10. Slack J. Risks of Ischaemic Heart-Disease in Familial Hyperlipoproteinaemic States. Lancet, 27 December 1969.
  11. McGill HC, McMaham A, Gidding SS. Preventing heart disease in the 21st century: implications of the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. Circulation 2008;117:1216-1227.
  12. McGill HC Jr, McMahan CA, Herderick EE, Tracy RE, Malcom GT, Zieske AW, Strong JP. Effects of coronary heart disease risk factors on atherosclerosis of selected regions of the aorta and right coronary artery. PDAY Research Group. Pathobiological Determinants of Atherosclerosis in Youth. Arterioscler Thromb Vasc Biol 2000;20(3):836-845.
  13. McGill HC, McMaham A, Gidding SS. Preventing heart disease in the 21st century: implications of the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. Circulation 2008;117:1216-1227.
  14. Ose L. Diagnostic, clinical, and therapeutic aspects of familial hypercholesterolemia in children. Semin Vasc Med. 2004;4:51-57.
  15. Kavey RW, Simons-Morton DG, and de Jesus JM, ed. Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents: Summary Report. Pediatrics 2011;128, Supplement 5.
  16. Haney EM, Huffman LH, Bougatsos C, Freeman M, Steiner RD, Nelson HD. Screening and treatment for lipid disorders in children and adolescents: systematic evidence review for the US Preventive Services Task Force. Pediatrics 2007;120(1):e189-e214.
  17. Ritchie S, Murphy E, Ice C, Cottrell LA, Minor V, Elliott E, and Neal W. Universal versus targeted blood cholesterol screening among youth: the CARDIAC project. Pediatrics 2010;126:260-265.
  18. Eissa MA, Wen E, Mihalopoulos NL, et al. Evaluation of AAP guidelines for cholesterol screening in youth: Project HeartBeat! Am J Prev Med 2009;37(1 Suppl):S71-S77.
  19. Kwiterovich PO, Barton BA, McMahon RP, et al. Effects of diet and sexual maturation on low-density lipoprotein cholesterol during puberty: the dietary intervention study in children (DISC). Circulation 1997;96:2526-2533.