A 5-year-old boy is undergoing a complete physical exam prior to starting kindergarten and the pediatrician notes some papules over the right Achilles tendon (Figure 193-1A). She also notes rings around the peripheral corneas of both eyes that could be arcus juvenilis (Figure 193-1B). The mom noticed the papules near the foot about 2 months ago but had not noticed anything unusual about the eyes. The pediatrician suspects that these findings could be secondary to elevated lipids and discovers that the mother has type 2 diabetes along with high cholesterol. The child is sent for a fasting lipid panel and blood sugar. The results confirm familial hypercholesterolemia (total cholesterol of 810 mg/dL and a low density lipoprotein of 507 mg/dL). The papules over the Achilles tendon are tendinous xanthomas and the eyes do show arcus juvenilis secondary to the elevated lipids. The child is referred to endocrinologist and the mother is told that all the family should be tested and everyone should be eating a low fat diet.
A. Tendinous xanthomas over the Achilles tendon of a 5-year-old boy with familial hypercholesterolemia. B. Arcus juvenilis secondary to elevated lipids in the same boy with familial hypercholesterolemia. The white ring is due to lipid infiltration of the corneal stroma and leaves some normal cornea at the limbus. (Used with permission from John Browning, MD.)
Hyperlipidemia refers to an elevated concentration of one or more of the measured serum lipid components (total cholesterol [TC], low-density lipid [LDL], high-density lipoprotein [HDL], and triglycerides [TGs]). Xanthomas are a skin manifestation of familial or severe secondary hyperlipidemia, although they can occur in patients with normal lipid levels. Hyperlipidemia is a major modifiable risk factor for cardiovascular disease.
Among young adults, ages 12 to 19 years, 20.3 percent have abnormal lipids; boys are more likely than girls to have at least 1 lipid abnormality (24.3% versus 15.9%, respectively).1
Patients with homozygous familial hypercholesterolemia (FH) (1 in 1 million persons worldwide) present in childhood with cutaneous xanthomas on the hands, wrists, elbows, knees, heels, or buttocks.2
In one population study, children of parents with coronary artery disease were more likely to be overweight and have dyslipidemia in childhood.3
Large epidemiological studies indicate that children’s lipid levels correlate with their adult family members levels.4
Etiology and Pathophysiology
Causes of primary lipid disorders most common seen in children and adolescents are familial combined hyperlipidemia and FH (heterozygous; Figure 193-1). Secondary causes include obesity, metabolic syndrome, hypothyroidism, hypopituitarism, diabetes mellitus (type 1 and type 2), polycystic ovary syndrome, juvenile rheumatoid arthritis, chronic renal disease including nephrotic syndrome, Kawasaki disease, and hepatitis.
Lipoproteins are complexes of lipids and proteins ...