Pediatric Lipid Disorders in Clinical Practice

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Multiple studies have revealed that the early stages of atherosclerosis begin in childhood. [1] If premature development of cardiovascular disease can be anticipated during childhood, the disease might be prevented. [2] The purpose of this article is to discuss the basic biology of lipoproteins, the pathophysiology of dyslipidemias, the interpretation of lipid levels in pediatric patients, dyslipidemia screening, and the management of pediatric lipid abnormalities.

For patient education information, see the Cholesterol Center, as well as Lowering High Cholesterol in Children, Cholesterol Charts, Lifestyle Cholesterol Management, Cholesterol-Lowering Medications, and Statins for Cholesterol.

The two major forms of circulating lipid in the body, triglyceride (TG) and cholesterol, are insoluble in plasma. However, these lipids can be transported throughout the bloodstream as lipoproteins when packaged with phospholipids and proteins (apoproteins). Lipoproteins have an outer core of cholesterol, phospholipids, and apoproteins and an inner core composed of TG and cholesterol ester (CE). Apoproteins function as (1) structural proteins, (2) proteins that make the lipoprotein particle soluble, (3) enzyme activators (eg, apoprotein C-II activates lipoprotein lipase [LPL], apoprotein A-I activates lecithin-cholesterol acyltransferase [LCAT]), and (4) ligands for receptors (eg, apoprotein B-100 binds to the low-density lipoprotein receptor [LDL-R], which is also known as the apoprotein B-100 – apoprotein E receptor).

Lipoproteins have been classified into five major classes, as depicted in the table below.

Table 1. Biology of Lipoproteins (Open Table in a new window)

Lipoprotein

Major Lipid Composition

Role in Normal Fasting Plasma

Measured Substance

High-density lipoprotein cholesterol (HDL-C)

Cholesterol

Antiatherogenic (involved in reverse cholesterol transport from the tissues to the liver)

HDL-C

LDL-C

Cholesterol

Major cholesterol carrier

Can be measured directly (direct LDL-C) or can be calculated*

Intermediate-density lipoprotein cholesterol (IDL-C)

TG and cholesterol

Intermediate between very–low density lipoprotein (VLDL) and low-density lipoprotein (LDL)

Not routinely measured; can be assessed by LPE† or measured by ultracentrifugation

VLDL

TG

Major TG carrier

TG‡

Chylomicron

TG

Absent

Not routinely measured; can be assessed by LPE or measured by ultracentrifugation

* Calculated using the Friedewald equation: LDL-C = Total cholesterol (TC) – HDL-C – TG/5

† LPE = Lipoprotein electrophoresis

‡ TG/5 is the estimate of the VLDL-C.

 

The classes of lipoprotein are not homogeneous in size or composition. For example, low-density lipoprotein cholesterol (LDL-C) can be divided into cholesterol-rich light, or buoyant, LDL-C and cholesterol-depleted, or dense, LDL-C. Dense LDL-C is more atherogenic than light LDL-C.

Lipoproteins are derived from the exogenous and the endogenous pathways. In the exogenous pathway, dietary lipids are consumed with meals; these lipids (predominantly TGs) are packaged by the intestinal mucosal cells into chylomicrons. Chylomicrons, which are TG rich, enter the lymphatic system. The thoracic duct empties into the vena cava, and chylomicrons systemically circulate. Apoprotein C-II, apoprotein B-48, and apoprotein E are the clinically important apoproteins of chylomicrons.

Apoprotein B-48 is a chylomicron structural protein. Chylomicrons bind to LPL via apoprotein C-II. Once acted on by LPL, which is attached to the luminal side of the capillary endothelium adjacent to muscle and adipose tissue, chylomicrons release TGs as monoglycerides and free fatty acids. Defects in apoprotein C-II or LPL can lead to defects in chylomicron clearance. Muscle normally burns the free fatty acids and monoglycerides for energy. Resynthesized TGs can be used for plasma and cell organelle membrane synthesis. Adipose tissue uses free fatty acids and monoglycerides to resynthesize TGs that are stored for future energy needs. As an alternative, adipocytes can use TGs in membrane synthesis, which is similar to muscle.

When the chylomicrons are reduced in TG content, they become remnants that are rapidly cleared by the liver (apoprotein E binds to the LDL receptor [LDL-R]). At this time, apoprotein C-II is passed to high-density lipoprotein (HDL) particles in the circulation. In the fasting state, chylomicrons and chylomicron remnants are not normally detected in plasma.

In the endogenous pathway, the liver produces VLDL. The clinically important apoproteins in VLDL are apoprotein C-II, apoprotein B-100, and apoprotein E. Like chylomicrons, VLDL interacts with LPL via apoprotein C-II to release TG, forming intermediate-density lipoprotein (IDL) particles. With the formation of IDL, apoprotein C-II is transferred to HDL particles. IDL particles are rapidly removed by the liver via apoprotein E interaction with the LDL-R. IDL particles may be further metabolized to LDL by continued removal of TG by hepatic lipase.

In the conversion from IDL to LDL, apoprotein E is shed and is picked up by HDL particles. LDL is removed by binding to the LDL-R. Approximately two thirds of circulating LDL is removed by the liver, and approximately one third is removed by extrahepatic tissues, including steroid-producing cells and cells within the subintimal space in which atheromatous plaques develop. In the subintimal space, the protective effect of circulating antioxidants is lost, and LDL is oxidized.

Oxidized LDL is removed by the scavenger receptor, which is different from the LDL-R. Smooth muscle cells and macrophages express scavenger receptors. This uptake of LDL is not regulated, and macrophages and smooth muscle cells can take up so much oxidized LDL and cholesterol that they become foam cells. Because oxidized LDL is toxic to cells, it can lead to early endothelial injury, allowing platelet adhesion and localized release of platelet-derived growth factor (PDGF). In contrast, when other cells have sufficient cholesterol, they down-regulate the LDL-R to decrease cholesterol uptake into the cell.

Table 2, below, depicts the Frederickson classification scheme, used to distinguish dyslipidemias.

Table 2. Frederickson Classification of Dyslipidemias (Open Table in a new window)

Phenotype

Elevated Particles

Major Lipid Increased

Frequency

I

Chylomicron

TG

Very rare

IIA

LDL

LDL-C

Common

IIB

LDL and VLDL

LDL-C, TG

Common

III

IDL and remnants

TC, TG

Rare

IV

VLDL

TG

Common

V

Chylomicron and VLDL

TG

Uncommon

 

The most common dyslipidemias are types IIA, IIB, and IV. Type I and type III hyperlipoproteinemia (HLP) are extremely rare in pediatric patients, and type V is uncommon.

Type I HLP is present when the TGs are predominantly elevated. TG levels may exceed 1000-2000 mg/dL, and levels as high as 25,000 mg/dL have been observed. Type I HLP is also termed chylomicron syndrome or hyperchylomicronemia syndrome. In type I HLP, the plasma infranatant on standing is clear, whereas the supernatant is cloudy because of elevated chylomicrons that float to the top of the plasma. Supernatants form only when chylomicrons are present. The presence of chylomicrons is best confirmed by obtaining plasma lipoprotein ultracentrifugation, performed by a referral laboratory that specializes in lipid analysis. Lipoprotein electrophoresis (LPE) is far less quantitative than ultracentrifugation.

Most cases of type I HLP are caused by congenital deficiency of LPL, congenital deficiency of apoprotein C-II, or an LPL inhibitor (eg, an anti-LPL autoantibody). In healthy children and adults, chylomicrons are rapidly cleared from the circulation after a meal. When LPL or apoprotein C-II is deficient, chylomicrons can be detected for more than 12 hours after a meal. The normal half-life of chylomicrons in plasma is approximately 17 minutes. Because TGs are not being cleared at the tissue level (eg, TG is not released from the chylomicrons to muscle and adipose tissue) in type I HLP, most chylomicrons are taken up by the liver and spleen, resulting in hepatosplenomegaly, macrophage uptake (foam cell formation), and the development of cutaneous xanthomas.

If prolonged hypertriglyceridemia is untreated, eruptive xanthomas (discrete 1-mm to 6-mm papules) may appear on the extensor surfaces of the extremities. Lipemia retinalis may also occur. The retinal vessels appear white-to-yellow in color because of the striking hyperchylomicronemia.

When TG levels exceed 1000-2000 mg/dL, the risk of pancreatitis is increased. Infants may present with colicky abdominal pain and even failure to thrive. In older children, acute pancreatitis can cause tremendous pain, nausea, vomiting, and even death if undetected and untreated. Recurrent pancreatitis can be debilitating.

In one study of patients with LPL deficiency, 80% presented before age 10 years, with 30% presenting before age one. In contrast, apoprotein C-II deficiency is usually diagnosed later in life (>13 years). Apoprotein C-II deficiency rarely presents in infancy.

At least 40 molecular defects in LPL and 12 different molecular defects in apoprotein C-II have been reported. Both LPL and apoprotein C-II deficiencies are inherited as autosomal recessive traits and affect approximately 1 in 1 million persons in the general population. Because LPL and apoprotein C-II deficiencies are inherited as autosomal recessive traits, the family history is generally unrevealing, although some parents of children with LPL or apoprotein C-II deficiency have been cousins. Carriers of LPL mutations are asymptomatic.

Note that lipemic serum can interfere with many laboratory determinations, including enzyme activity measurements, antigen-antibody assays, and various spectrophotometric assays.

In children, type IIA HLP is defined by LDL-C concentrations of 130 mg/dL or higher. The plasma is clear in type IIA HLP because LDL particles are not large enough to scatter light, as opposed to IDL, VLDL, or lipoprotein remnants that are large enough to cause turbidity.

In type IIB HLP, TG levels (VLDL levels) are elevated to 125 mg/dL or higher, and LDL-C levels are also elevated. If the TG level is typically 300-400 mg/dL or higher, the plasma appears visibly turbid (lipemic).

Familial hypercholesterolemia (FH) is an autosomal dominant disorder characterized by elevated LDL-C levels with or without a concurrent elevation in TG levels. Thus, individuals with FH may display a type IIA or B phenotype. FH affects approximately one in 500 persons in the general population. Besides premature cardiovascular disease, clinical findings in adults include tendon xanthomas (especially involving the Achilles tendons and the extensor tendons of the hands) and arcus senilis (involving the cornea). FH results from an inherited defect in the LDL-R. Because the LDL-R also clears IDL, and because VLDL is the precursor of IDL and LDL, patients with FH may also display elevations in IDL and VLDL.

If an individual inherits two defective alleles of the LDL-R gene (homozygous FH), LDL production increases by approximately 200-300%. Adults who are heterozygous for FH have two- to three-fold higher total cholesterol (TC) levels of 300-600 mg/dL, and LDL-C levels are commonly 250 mg/dL or higher. Patients who are homozygous for FH have TC levels of 600-1500 mg/dL. Homozygous FH leads to extremely premature and hazardous atherosclerosis. In addition, aortic valvar disease can occur in children with homozygous FH.

Besides valve dysfunction, the ostia of the coronary arteries can become obstructed. Fortunately, homozygous FH is very rare, affecting only one in 1 million persons. Children with homozygous FH have suffered myocardial infarctions as early as age 3 years. Death during adolescence is common. Homozygous FH should thus be strongly suspected in deaths from myocardial infarction in individuals aged 20 years or younger.

In heterozygous FH, affected family members have elevated LDL-C concentrations beginning early in life. Cord blood TC and LDL-C levels are already elevated. Untreated males with FH often develop cardiovascular disease in the fourth or fifth decade of life, but the disease can manifest in teenagers. The mean age of death in males with untreated FH is 45 years. Untreated women with FH usually have onset of cardiovascular disease in the fifth or sixth decade of life. Of persons who have survived myocardial infarctions that occurred when they were younger than 60 years, 5% have FH.

A defect in apoprotein B-100 is phenotypically similar to FH and occurs with a similar frequency. Elevated LDL-C levels result when the apoprotein B molecule is defective, even if the LDL-R molecule is normal. In FH, IDL and VLDL concentrations can be elevated because IDL is cleared via the LDL-R; however, in familial defective apoprotein B-100, because the LDL-R molecule is normal, IDL, VLDL, and TG levels are usually normal. In contrast to FH, tendon xanthomas and arcus senilis may be absent in patients with defective apoprotein B-100. Modest hypercholesterolemia (250-300 mg/dL) is usually present, with a TC level lower than in adults with FH (mean TC concentration in defective apoprotein B-100 is 269 mg/dL, vs approximately 360 mg/dL in FH). LDL-C levels are raised by approximately 70 mg/dL. As in FH, patients with familial defective apoprotein B-100 may develop premature cardiovascular disease.

Familial defective apoprotein B-100 and FH can be very difficult to clinically differentiate when patients with FH display a type IIA phenotype; however, in the absence of secondary conditions that raise TG levels, the presence of a type IIB phenotype essentially excludes familial defective apoprotein B-100.

Familial combined hyperlipidemia (FCH) is inherited as an autosomal dominant trait. The etiology of FCH appears to be an overproduction of apoprotein B–containing particles (VLDL, LDL, or both). Affected individuals may exhibit type IIA, type IIB, or type IV phenotypes. In a single family with FCH, some individuals may display isolated elevations in TC/LDL (type IIA HLP) or TG (type IV HLP) levels, whereas other affected members may have a combined hyperlipidemia (increased LDL-C and TG levels [type IIB HLP]). The co-occurrence of FCH plus hypertension has been called familial dyslipidemic hypertension. Similar to FH, premature cardiovascular disease can occur in patients with FCH. Overall, FCH affects approximately 1 in 200-300 persons in the general population and occurs in approximately 15% of individuals younger than 60 years who survive a myocardial infarction.

Other causes of type IIA or IIB phenotypes include hypothyroidism, nephrosis, biliary tract disease, and diabetes mellitus. In hypothyroidism, hepatic LDL-R expression is reduced, leading to elevated LDL-C levels because of reduced LDL clearance. Lipoprotein production is typically increased in patients with nephrosis. This may be a compensation for hypoalbuminemia. With glycation of apoprotein B in patients with diabetes mellitus and increased VLDL synthesis, LDL-C levels commonly rise.

Type III HLP (also known as remnant removal disease, remnant lipoprotein disease, or dysbetalipoproteinemia) is estimated to affect approximately 1 in 5000 persons in the general population but rarely manifests in children. Type III HLP is caused by increases in IDL and remnant lipoproteins and is manifested by approximately equal increases in total cholesterol and TGs.

Palmar xanthomas (xanthoma striata palmaris) may occur in type III HLP and are not observed in other disorders. Genetic and environmental factors both influence the development of type III HLP. The entity should be considered when tuberous xanthomas, palmar xanthomas, or both are noted, and the patient may be obese or have underling diseases such as diabetes mellitus, hypothyroidism, alcoholism, and renal or hepatic disease. Type III HLP can be inherited as a recessive trait or, less commonly, as a dominant trait.

Most adults with type III HLP are homozygous for apoprotein E-2 (one of the 3 isoforms of apoprotein E). Adults with type III HLP are at markedly increased risk for cardiovascular disease and, particularly, peripheral vascular disease.

In type IV HLP, a predominant increase in VLDL TGs is observed; however, levels are lower (eg, < 1000 mg/dL) than in HLP types I or V.

Hypertriglyceridemia (usually the type IV HLP phenotype) is frequently observed in children with obesity, diabetes, or both conditions. In type 1 diabetes mellitus, hypertriglyceridemia results from absolute insulin deficiency, whereas in children with obesity and type 2 diabetes mellitus, insulin resistance is the root cause, combined with relative insulin deficiency. Other causes of insulin resistance, including renal disease, liver disease, ethanol abuse, pregnancy, endocrinopathies (eg, Cushing disease, hypothyroidism, acromegaly), and drugs (eg, glucocorticoids, growth hormone, androgens, thiazides, beta blockers, estrogen, HIV protease inhibitors), may also lead to hypertriglyceridemia.

Similar to insulin, thyroid hormone regulates LPL activity; hypothyroidism can cause elevated TG levels by lowering LPL activity.

The combination of type IV HLP and low HDL-C (eg, hypoalphalipoproteinemia) are typical findings in the metabolic syndrome. The metabolic syndrome is a constellation of findings related to reduced insulin sensitivity most commonly caused by centripetal and abdominal obesity. Besides dyslipidemia, features of the metabolic syndrome include hyperinsulinism, dysglycemia (eg, impaired glucose tolerance, impaired fasting glucose or type 2 diabetes), hypertension, hyperuricemia, hyperandrogenism in women, polycystic ovary syndrome, propensity to thrombosis (because of increased plasminogen activator inhibitor levels), and elevated ferritin concentrations. Adults with the metabolic syndrome are at greatly increased risk for cardiovascular disease.

Two inherited causes of a type IV phenotype include familial hypertriglyceridemia and FCH. Familial hypertriglyceridemia is rarely expressed in childhood unless another underlying cause of hypertriglyceridemia is present. About 15% of patients with premature cardiovascular disease have hypertriglyceridemia.

Type V HLP results when two or more causes of type IV HLP combine to produce chylomicronemia and elevated VLDL levels, which push TG levels to 1000 mg/dL or higher. Plasma samples in patients with type V HLP display a turbid infranatant and a cloudy supernatant.

The differential diagnosis of a depressed HDL-C level includes familial disorders, genetic disorders, smoking, obesity, hypertriglyceridemia, renal failure, and drugs (eg, anabolic steroids, progestins, beta blockers, thiazides), with male sex and a sedentary lifestyle being additional risk factors for low HDL-C. In familial hypoalphalipoproteinemia (ie, low HDL-C) and Tangier disease, depressed apoprotein A-I levels are found. Other rare genetic causes of low HDL-C levels include fish-eye disease and lecithin-cholesterol acyl transferase (LCAT) deficiency. In fish-eye disease, patients have TG elevations to 250-300 mg/dL, severely depressed HDL-C levels, and corneal opacities. In LCAT deficiency, cholesterol esters cannot be formed; thus, cholesterol does not move into the core of the HDL particle disc.

Causes of acquired low LDL-C levels include malnutrition from starvation or malabsorption, hyperthyroidism, chronic anemia, severe hepatic dysfunction, and acute severe stress (eg, burns, trauma, myocardial infarction). Genetic forms of hypolipidemia are very rare but are potentially serious. Such conditions include abetalipoproteinemia (autosomal recessive), homozygous hypobetalipoproteinemia, heterozygous hypobetalipoproteinemia (with or without GI tract or neurologic symptoms), abetalipoproteinemia with normotriglyceridemia, and chylomicron retention disease. Low cholesterol levels secondary to deficiency of 7-dehydrocholesterol-δ-7 reductase are seen in Smith-Lemli-Opitz syndrome associated with mental retardation and ambiguous genitalia.

Aggoun Y, Bonnet D, Sidi D, et al. Arterial mechanical changes in children with familial hypercholesterolemia. Arterioscler Thromb Vasc Biol. 2000 Sep. 20(9):2070-5. [Medline].

Cortner JA, Coates PM, Liacouras CA, Jarvik GP. Familial combined hyperlipidemia in children: clinical expression, metabolic defects, and management. Curr Probl Pediatr. 1994 Oct. 24(9):295-305. [Medline].

Nordestgaard BG, Benn M, Schnohr P, Tybjaerg-Hansen A. Nonfasting triglycerides and risk of myocardial infarction, ischemic heart disease, and death in men and women. JAMA. 2007 Jul 18. 298(3):299-308. [Medline].

Bansal S, Buring JE, Rifai N, Mora S, Sacks FM, Ridker PM. Fasting compared with nonfasting triglycerides and risk of cardiovascular events in women. JAMA. 2007 Jul 18. 298(3):309-16. [Medline].

Mora S, Rifai N, Buring JE, Ridker PM. Fasting compared with nonfasting lipids and apolipoproteins for predicting incident cardiovascular events. Circulation. 2008 Sep 2. 118(10):993-1001. [Medline].

Langsted A, Freiberg JJ, Nordestgaard BG. Fasting and nonfasting lipid levels: influence of normal food intake on lipids, lipoproteins, apolipoproteins, and cardiovascular risk prediction. Circulation. 2008 Nov 11. 118(20):2047-56. [Medline].

Mora S, Rifai N, Buring JE, Ridker PM. Comparison of LDL cholesterol concentrations by Friedewald calculation and direct measurement in relation to cardiovascular events in 27,331 women. Clin Chem. 2009 May. 55(5):888-94. [Medline].

Mora S. Non-fasting blood testing for lipid screening in children result in statistically significant, but not clinically significant, changes in lipid. Evidence-Based Medicine. 2012. doi:10.1136/ebmed-:2011-100471.

[Guideline] National Cholesterol Education Program. Highlights of the Report of the Expert Panel on Blood Cholesterol Levels in Children and Adolescents. U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health. 1991;1-11:NIH Publication No. 91-2731; September.

[Guideline] National Cholesterol Education Program. Report of the Expert Panel on Blood Cholesterol Levels in Children and Adolescents. 1991;US Department of Health and Human Services: NIH Publication No. 91-2732.

[Guideline] National Cholesterol Education Program. Summary of the second report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel II). JAMA. 1993 Jun 16. 269(23):3015-23. [Medline].

[Guideline] National Cholesterol Education Program. Executive Summary of The Third Report of The National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, And Treatment of High Blood Cholesterol In Adults (Adult Treatment Panel III). JAMA. 2001 May 16. 285(19):2486-97. [Medline].

[Guideline] Expert panel on integrated guidelines for cardiovascular health and risk reduction in children and adolescents: summary report. Pediatrics. 2011 Dec. 128 Suppl 5:S213-56. [Medline]. [Full Text].

Jellinger PS, Smith DA, Mehta AE, Ganda O, Handelsman Y, Rodbard HW. American Association of Clinical Endocrinologists’ Guidelines for Management of Dyslipidemia and Prevention of Atherosclerosis. Endocr Pract. 2012 Mar-Apr. 18 Suppl 1:1-78. [Medline].

[Guideline] USDA, USDHHS. Dietary Guidelines for Americans, 2010. 7th ed. Washington, DC: US Government Printing Office; 2010. [Full Text].

[Guideline] Kavey RE, Allada V, Daniels SR, et al. Cardiovascular risk reduction in high-risk pediatric patients: a scientific statement from the American Heart Association Expert Panel on Population and Prevention Science; the Councils on Cardiovascular Disease in the Young, Epidemiology and Prevention, Nutrition, Physical Activity and Metabolism, High Blood Pressure Research, Cardiovascular Nursing, and the Kidney in Heart Disease; and the Interdisciplinary Working Group on Quality of Care and Outcomes Research: endorsed by the American Aca… Circulation. 2006 Dec 12. 114(24):2710-38. [Medline].

Stein EA, Marais AD, Szamosi T, et al. Colesevelam hydrochloride: efficacy and safety in pediatric subjects with heterozygous familial hypercholesterolemia. J Pediatr. 2010 Feb. 156(2):231-6.e1-3. [Medline].

Colletti RB, Neufeld EJ, Roff NK, McAuliffe TL, Baker AL, Newburger JW. Niacin treatment of hypercholesterolemia in children. Pediatrics. 1993 Jul. 92(1):78-82. [Medline].

Christian JB, Juneja MX, Meadowcroft AM, et al. Prevalence, characteristics, and risk factors of elevated triglyceride levels in US children. Clin Pediatr (Phila). 2011 Dec. 50(12):1103-9. [Medline].

[Guideline] American Academy of Pediatrics. American Academy of Pediatrics Committee on Nutrition: Indications for cholesterol testing in children. Pediatrics. 1989 Jan. 83(1):141-2. [Medline].

[Guideline] American Heart Association. Diagnosis and treatment of primary hyperlipidemia in childhood. Diagnosis and treatment of primary hyperlipidemia in childhood. A Joint Statement for Physicians by the Committee on Atherosclerosis and Hypertension in Childhood of the Council of Cardiovascular Disease in the Young and the Nutrition Committee, American Heart Association. Circulation. 1986 Nov. 74(5):1181A-1188A. [Medline].

Berenson GS, ed. Causation of Cardiovascular Risk Factors in Children. Perspectives on Cardiovascular Risk in Early Life. New York, NY: Raven Press; 1986.

Berenson GS, Srinivasan SR, Nicklas TA, Webber LS. Cardiovascular risk factors in children and early prevention of heart disease. Clin Chem. 1988. 34(8B):B115-22. [Medline].

Cholesterol screening in childhood. Lancet. 1991 Jun 29. 337(8757):1574-5. [Medline].

[Guideline] Daniels SR, Greer FR. Lipid screening and cardiovascular health in childhood. Pediatrics. 2008 Jul. 122(1):198-208. [Medline].

Daniels SR, Morrison JA, Sprecher DL. Perspectives on cholesterol screening programs for children. J Pediatr. 1991 Nov. 119(5):834-8. [Medline].

Dennison BA, Kikuchi DA, Srinivasan SR, Webber LS, Berenson GS. Parental history of cardiovascular disease as an indication for screening for lipoprotein abnormalities in children. J Pediatr. 1989 Aug. 115(2):186-94. [Medline].

Dietary Intervention Study in Children. Efficacy and safety of lowering dietary intake of fat and cholesterol in children with elevated low-density lipoprotein cholesterol. The Dietary Intervention Study in Children (DISC). The Writing Group for the DISC Collaborative Research Group. JAMA. 1995 May 10. 273(18):1429-35. [Medline].

Ducobu J, Brasseur D, Chaudron JM, et al. Simvastatin use in children. Lancet. 1992 Jun 13. 339(8807):1488. [Medline].

Enos WF, Holmes RH, Beyer J. Coronary disease among United States soldiers killed in action in Korea. JAMA. 1953. 152:1090-3.

Farah JR, Kwiterovich PO Jr, Neill CA. Dose-effect relation of cholestryamine in children and young adults with familial hypercholesterolaemia. Lancet. 1977 Jan 8. 1(8002):59-63. [Medline].

Gillman MW, Lannon CM. Screening for hypercholesterolemia in children: the missing links. Ann Epidemiol. 1991 Nov. 1(6):559-65. [Medline].

Glueck CJ. Pediatric primary prevention of atherosclerosis. N Engl J Med. 1986 Jan 16. 314(3):175-7. [Medline].

Griffin TC, Christoffel KK, Binns HJ, McGuire PA. Family history evaluation as a predictive screen for childhood hypercholesterolemia. Pediatric Practice Research Group. Pediatrics. 1989 Aug. 84(2):365-73. [Medline].

Henry JB, ed. Clinical Diagnosis and Management by Laboratory Methods. Philadelphia, PA: WB Saunders; 2001. 242.

Jacobson MS, Lillienfeld DE. The pediatrician’s role in atherosclerosis prevention. J Pediatr. 1988 May. 112(5):836-41. [Medline].

Kannel WB, Dawber TR. Atherosclerosis as a pediatric problem. J Pediatr. 1972 Apr. 80(4):544-54. [Medline].

Knipscheer HC, Boelen CC, Kastelein JJ, et al. Short-term efficacy and safety of pravastatin in 72 children with familial hypercholesterolemia. Pediatr Res. 1996 May. 39(5):867-71. [Medline].

Kwiterovich PO Jr. Diagnosis and management of familial dyslipoproteinemia in children and adolescents. Pediatr Clin North Am. 1990 Dec. 37(6):1489-523. [Medline].

Lambert M, Lupien PJ, Gagne C, et al. Treatment of familial hypercholesterolemia in children and adolescents: effect of lovastatin. Canadian Lovastatin in Children Study Group. Pediatrics. 1996 May. 97(5):619-28. [Medline].

Lauer RM, Clarke WR. Use of cholesterol measurements in childhood for the prediction of adult hypercholesterolemia. The Muscatine Study. JAMA. 1990 Dec 19. 264(23):3034-8. [Medline].

Leeson CP, Whincup PH, Cook DG, et al. Cholesterol and arterial distensibility in the first decade of life: a population-based study. Circulation. 2000 Apr 4. 101(13):1533-8. [Medline].

McCrindle BW, O’Neill MB, Cullen-Dean G, Helden E. Acceptability and compliance with two forms of cholestyramine in the treatment of hypercholesterolemia in children: a randomized, crossover trial. J Pediatr. 1997 Feb. 130(2):266-73. [Medline].

McCrindle BW, Urbina EM, Dennison BA, et al. Drug therapy of high-risk lipid abnormalities in children and adolescents: a scientific statement from the American Heart Association Atherosclerosis, Hypertension, and Obesity in Youth Committee, Council of Cardiovascular Disease in the Young, with the Council on Cardiovascular Nursing. Circulation. 2007 Apr 10. 115(14):1948-67. [Medline]. [Full Text].

McGill HC Jr, McMahan CA, Herderick EE, et al. 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 Mar. 20(3):836-45. [Medline].

McGill HC Jr, McMahan CA, Zieske AW, et al. Association of Coronary Heart Disease Risk Factors with microscopic qualities of coronary atherosclerosis in youth. Circulation. 2000 Jul 25. 102(4):374-9. [Medline].

McGill HC Jr, McMahan CA, Zieske AW, et al. Associations of coronary heart disease risk factors with the intermediate lesion of atherosclerosis in youth. The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group. Arterioscler Thromb Vasc Biol. 2000 Aug. 20(8):1998-2004. [Medline].

McNamara DG. Can (should) the pediatrician wage preventive medicine war against coronary heart disease?. Am J Dis Child. 1986 Oct. 140(10):985-6. [Medline].

McNamara JJ, Molot MA, Stremple JF, Cutting RT. Coronary artery disease in combat casualties in Vietnam. JAMA. 1971 May 17. 216(7):1185-7. [Medline].

Newman TB, Browner WS, Hulley SB. Childhood cholesterol screening: contraindicated. JAMA. 1992 Jan 1. 267(1):100-1; discussion 101-2. [Medline].

Newman TB, Browner WS, Hulley SB. The case against childhood cholesterol screening. JAMA. 1990 Dec 19. 264(23):3039-43. [Medline].

Newman WP 3rd, Freedman DS, Voors AW, et al. Relation of serum lipoprotein levels and systolic blood pressure to early atherosclerosis. The Bogalusa Heart Study. N Engl J Med. 1986 Jan 16. 314(3):138-44. [Medline].

Nora JJ. Identifying the child at risk for coronary disease as an adult: A strategy for prevention. J Pediatr. 1980 Nov. 97(5):706-14. [Medline].

Relationship of atherosclerosis in young men to serum lipoprotein cholesterol concentrations and smoking. A preliminary report from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group. JAMA. 1990 Dec 19. 264(23):3018-24. [Medline].

Santamarina-Fojo S, Brewer HB Jr. The familial hyperchylomicronemia syndrome. New insights into underlying genetic defects. JAMA. 1991 Feb 20. 265(7):904-8. [Medline].

Schieken RM. Why screen children for blood cholesterol levels?. Ann Epidemiol. 1991 Nov. 1(6):571-4. [Medline].

Sinzinger H, Schmid P, Pirich C, et al. Treatment of hypercholesterolaemia in children. Lancet. 1992 Aug 29. 340(8818):548-9. [Medline].

Starc TJ, Belamarich PF, Shea S, et al. Family history fails to identify many children with severe hypercholesterolemia. Am J Dis Child. 1991 Jan. 145(1):61-4. [Medline].

Stein EA, Myers GL. Lipids, lipoproteins, and apoproteins. Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. Philadelphia: WB Saunders Co; 1994. 1002-1093.

Steiner NJ, Neinstein LS, Pennbridge J. Hypercholesterolemia in adolescents: effectiveness of screening strategies based on selected risk factors. Pediatrics. 1991 Aug. 88(2):269-75. [Medline].

Strong JP. Landmark perspective: Coronary atherosclerosis in soldiers. A clue to the natural history of atherosclerosis in the young. JAMA. 1986 Nov 28. 256(20):2863-6. [Medline].

Strong JP, McGill HC Jr. The pediatric aspects of atherosclerosis. J Atheroscler Res. 1969 May-Jun. 9(3):251-65. [Medline].

Stuhldreher WL, Orchard TJ, Donahue RP, Kuller LH, Gloninger MF, Drash AL. Cholesterol screening in childhood: sixteen-year Beaver County Lipid Study experience. J Pediatr. 1991 Oct. 119(4):551-6. [Medline].

Tonstad S. A rational approach to treating hypercholesterolaemia in children. Weighing the risks and benefits. Drug Saf. 1997 May. 16(5):330-41. [Medline].

Tonstad S. Role of lipid-lowering pharmacotherapy in children. Paediatr Drugs. 2000 Jan-Feb. 2(1):11-22. [Medline].

Tonstad S, Knudtzon J, Sivertsen M, Refsum H, Ose L. Efficacy and safety of cholestyramine therapy in peripubertal and prepubertal children with familial hypercholesterolemia. J Pediatr. 1996 Jul. 129(1):42-9. [Medline].

Virmani R, Robinowitz M, Geer JC, Breslin PP, Beyer JC, McAllister HA. Coronary artery atherosclerosis revisited in Korean war combat casualties. Arch Pathol Lab Med. 1987 Oct. 111(10):972-6. [Medline].

Winter WE, Bertholf RL, Riley WJ, Maclaren NK, Obata M, Allen L. Hypercholesterolemia. A common problem in Florida school-age children and adolescents. Ann N Y Acad Sci. 1991. 623:472-5. [Medline].

Winter WE, Hardt NS. Pediatric approach to prevention of coronary heart disease. J Fla Med Assoc. 1993 Oct. 80(10):679-83. [Medline].

Lipoprotein

Major Lipid Composition

Role in Normal Fasting Plasma

Measured Substance

High-density lipoprotein cholesterol (HDL-C)

Cholesterol

Antiatherogenic (involved in reverse cholesterol transport from the tissues to the liver)

HDL-C

LDL-C

Cholesterol

Major cholesterol carrier

Can be measured directly (direct LDL-C) or can be calculated*

Intermediate-density lipoprotein cholesterol (IDL-C)

TG and cholesterol

Intermediate between very–low density lipoprotein (VLDL) and low-density lipoprotein (LDL)

Not routinely measured; can be assessed by LPE† or measured by ultracentrifugation

VLDL

TG

Major TG carrier

TG‡

Chylomicron

TG

Absent

Not routinely measured; can be assessed by LPE or measured by ultracentrifugation

* Calculated using the Friedewald equation: LDL-C = Total cholesterol (TC) – HDL-C – TG/5

† LPE = Lipoprotein electrophoresis

‡ TG/5 is the estimate of the VLDL-C.

Phenotype

Elevated Particles

Major Lipid Increased

Frequency

I

Chylomicron

TG

Very rare

IIA

LDL

LDL-C

Common

IIB

LDL and VLDL

LDL-C, TG

Common

III

IDL and remnants

TC, TG

Rare

IV

VLDL

TG

Common

V

Chylomicron and VLDL

TG

Uncommon

Children (< 20 y)

Desirable level (mg/dL)

Borderline level (mg/dL)

Undesirable level (mg/dL)

TC

< 170

170-199

≥200

LDL-C

< 110

110-129

≥130

HDL-C*

>45

35-45

< 35

TG

< 125

≥125

Adults (≥20 y)

Desirable level (mg/dL)

Borderline level (mg/dL)

Undesirable level (mg/dL)

TC

< 200

200-239

≥240

LDL-C§

< 130

130-159

≥160

HDL-C||

≥40

< 40

TGs

< 150

150-199

≥200

* This was not established by NCEP; these values were the adult cutpoints used at the time that the pediatric NCEP guidelines were established.

This was not established by NCEP; a TG level of 125 mg/dL approximates the mean 95th percentile for TGs in boys and girls during childhood and adolescence.

In March of 2001, cutoff points for desirable and undesirable cholesterol, HDL-C, and other levels were revised in the Adult Treatment Panel III (ATPIII). [12]

§ The optimal LDL-C concentration is less than 100 mg/dL; in patients with cardiovascular disease or diabetes, the optimal LDL-C level is less than 70 mg/dL.

|| If the HDL-C level is 60 mg/dL or higher, one risk factor for coronary heart disease can be subtracted in adults.

Age

Dietary Recommendations

Birth to 6 months

Infants should be exclusively breastfed until age 6 months

6-12 months

Continue breastfeeding until at least 12 months of age (or feed iron-fortified formula if unable to breastfeed), gradually adding solid foods

No restriction in fat intake without medical recommendation

Water should be encouraged

Limit other types of drinks to 100% fruit juice, intake of which should be limited to 4 ounces/day or less

No sweetened beverages

12-24 months

Switch to reduced fat milk (2% to fat free)

Limit or avoid sugar-sweetened drinks

Water should be encouraged

Transition to table food with total fat content of 30% of daily kcal/estimated energy requirement (EER), saturated fat content of 8-10% of daily kcal/EER, and monounsaturated and polyunsaturated fat content of up to 20% of daily kcal/EER

Avoid trans fat as much as possible

Total daily cholesterol less than 300 mg

2-10 years

Fat-free milk

Limit or avoid sugar-sweetened drinks

Water should be encouraged

Limit total fat to 25-30% of daily kcal/EER, saturated fat to 8-10% of daily kcal/EER, and monounsaturated and polyunsaturated fat to up to 20% of daily kcal/EER

Avoid trans fat as much as possible

Total daily cholesterol less than 300 mg

Encourage high dietary fiber intake from foods

11-21 years

Fat-free milk

Limit or avoid sugar-sweetened drinks

Water should be encouraged

Limit total fat to 25-30% of daily kcal/EER, saturated fat to 8-10% of daily kcal/EER, and monounsaturated and polyunsaturated fat to up to 20% of daily kcal/EER

Avoid trans fat as much as possible

Total daily cholesterol less than 300 mg

Encourage high dietary fiber intake from foods

Generic Name

Adult Dose

Pediatric Dose

Dose Adjustment for Renal Insufficiency or Coadministration with Food or Drugs That Decrease Clearance*

Lovastatin (Mevacor)

Initial: 20 mg/d orally every bedtime

Followed by: 10-80 mg/d orally every bedtime or divided twice daily

10-17 years: 10-20 mg/d orally every bedtime initially; maintenance dosage ranges from 10-40 mg/d

Not to exceed 20 mg/d

Simvastatin (Zocor)

Initial: 5-10 mg/d orally every bedtime

Followed by 5-80 mg/d orally every bedtime or divided twice daily

10-17 years: 10 mg/d orally every bedtime initially; maintenance dosage ranges from 10-40 mg/d

5 mg/d initially; not to exceed 20 mg/d

Pravastatin (Pravachol)

Initial: 10-20 mg/d orally every bedtime

Followed by 5-40 mg/d orally every bedtime

8-13 years: 20 mg orally every day

14-18 years: 40 mg orally every day

Initiate at 5-10 mg/d; not to exceed 20 mg/d (also decrease with hepatic impairment)

Fluvastatin (Lescol)

Initial: 20-30 mg/d orally every bedtime

Followed by 20-80 mg/d orally every bedtime; for 80 mg/d, divide twice daily

10-16 years: 20 mg orally every day initially; maintenance dosage ranges from 20-80 mg/d

No adjustment

Atorvastatin (Lipitor)

Initial: 10 mg/d PO orally every bedtime

Followed by 10-80 mg/d orally every bedtime

10-17 years: 10 mg orally every day initially; maintenance dosages do not exceed 20 mg/d

No adjustment for renal insufficiency; decrease dose or avoid with drugs that decrease clearance

Rosuvastatin (Crestor)

10-20 mg orally every day initially; maintenance dosage range is 5-40 mg/d

Not established

5 mg orally every day initially; not to exceed 10 mg/d

* Renal insufficiency is indicated by a creatinine clearance of less than 30 mL/min; agents known to decrease HMG-CoA–reductase inhibitor clearance include grapefruit juice, gemfibrozil, ritonavir, cyclosporine, danazol, amiodarone, azole antifungals, macrolide antibiotics, and verapamil.

Drug Name

Approved Indications

Adult Dose

Gemfibrozil (Lopid)

HLP types IIB, IV, and V

600 mg orally twice daily (ie, 1200 mg total daily dose) 30 min before meals (ie, before breakfast and dinner)

Fenofibrate (Tricor)

HLP types IIA, IIB, IV and V

Initial: 67 mg/d orally; not to exceed 67 mg orally twice daily

Henry J Rohrs, III, MD Assistant Professor, Department of Pediatrics, Division of Pediatric Endocrinology, University of Florida College of Medicine

Henry J Rohrs, III, MD is a member of the following medical societies: American Association of Clinical Endocrinologists, Pediatric Endocrine Society

Disclosure: Nothing to disclose.

Desmond Schatz, MBBCh, MD Professor, Medical Director of Diabetes Center, Department of Pediatrics, Division of Endocrinology, University of Florida College of Medicine

Desmond Schatz, MBBCh, MD is a member of the following medical societies: American Academy of Pediatrics, American Diabetes Association, Endocrine Society, Florida Medical Association, Pediatric Endocrine Society, Society for Pediatric Research

Disclosure: Serve(d) as a speaker or a member of a speakers bureau for: Sanofi Aventis<br/>Received income in an amount equal to or greater than $250 from: Sanofi Aventis.

William E Winter, MD Professor, Departments of Pathology and Laboratory Medicine and Pediatrics, University of Florida College of Medicine

William E Winter, MD is a member of the following medical societies: American Diabetes Association, American Association for Clinical Chemistry

Disclosure: Nothing to disclose.

Vanessa Davis, MD Fellow, Department of Pediatrics, Division of Endocrinology, University of Florida

Vanessa Davis, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Clinical Endocrinologists, American Diabetes Association, American Medical Association, Endocrine Society, Pediatric Endocrine Society, National Medical Association

Disclosure: Nothing to disclose.

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

John W Moore, MD, MPH Professor of Clinical Pediatrics, Section of Pediatic Cardiology, Department of Pediatrics, University of California San Diego School of Medicine; Director of Cardiology, Rady Children’s Hospital

John W Moore, MD, MPH is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, Society for Cardiovascular Angiography and Interventions

Disclosure: Nothing to disclose.

Stuart Berger, MD Executive Director of The Heart Center, Interim Division Chief of Pediatric Cardiology, Lurie Childrens Hospital; Professor, Department of Pediatrics, Northwestern University, The Feinberg School of Medicine

Stuart Berger, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American College of Chest Physicians, American Heart Association, Society for Cardiovascular Angiography and Interventions

Disclosure: Nothing to disclose.

Christopher Johnsrude, MD, MS Chief, Division of Pediatric Cardiology, University of Louisville School of Medicine; Director, Congenital Heart Center, Kosair Children’s Hospital

Christopher Johnsrude, MD, MS is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology

Disclosure: Nothing to disclose.

Pediatric Lipid Disorders in Clinical Practice

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