Background: Previous reported serum lipid levels in children and adolescents with familial hypercholesterolemia are uncertain. Reasons are that the diagnosis may have been uncertain and that the reported lipid levels have been mainly from patients treated at tertiary referral centres.
Material and methods: The serum lipid levels in 434 children and adolescents (2-18 years) who had undergone molecular genetic testing for familial hypercholesterolemia as part of cascade genetic screening, were measured.
Results: 196/434 (45.2%) were heterozygous for the mutation in the LDL receptor gene that had been identified in the family, while 238/434 (54.8%) were not heterozygous. Those who were heterozygous had mean total serum cholesterol levels of 7.40 (+/- 1.41) mmol/L and LDL cholesterol of 5.60 (+/- 1.38) mmol/L. These values were 1.70 (p < 0.001) and 2.19 (p < 0.001) times higher than the corresponding values in those who were not heterozygous. A total serum cholesterol level of 5.5 mmol/L had a high sensitivity and specificity for the diagnosis of familial hypercholesterolemia.
Interpretation: Familial hypercholesterolemia should mainly be diagnosed by molecular genetic testing. If the underlying mutation cannot be identified a total serum cholesterol value of 5.5 mmol/L and an LDL cholesterol value of 3.5 mmol/L, should be used to diagnose children and adolescents.