Objective: To examine serum levels of retinol, 25-hydroxyvitamin D, and alpha-tocopherol and their potential determinants in familial hypercholesterolemia (FH).
Subjects: Study 1: 151 boys and girls with FH aged 7 to 16 years who were following a lipid-reduced diet but not taking lipid-lowering drugs. Study 2: 87 boys and girls with FH, of whom 24 were taking bile acid-binding resins in addition to the diet, and 30 age- and sex-matched control subjects.
Design: Cross-sectional survey.
Setting: Lipid referral clinic.
Results: None of the subjects had suboptimal retinol or 25-hydroxyvitamin D levels. Only one girl had a low alpha-tocopherol level and alpha-tocopherol/lipid ratio. In multiple regression analysis, pubertal onset and gender were associated with retinol and 25-hydroxyvitamin D levels. The triglyceride level was positively related to level of retinol, and body mass index was inversely related to 25-hydroxyvitamin D level. Vitamin supplementation was positively related to 25-hydroxyvitamin D level and the alpha-tocopherol/lipid ratio. This ratio was lower in subjects whose total cholesterol level was above the median (8.0 mmol/L (310 mg/dl)) than in subjects whose cholesterol level was below the median (p = 0.01). In study 2, the alpha-tocopherol/lipid ratio in control subjects (median, 5.1 mumol/mmol) was higher than in subjects with FH who were not taking resins (median, 3.3 mumol/mmol; p < 0.05) but similar to the ratio in treated subjects (median, 5.4 mumol/mmol).
Conclusions: Pubertal onset, gender, lipid levels, vitamin supplementation, and body mass index are significant predictors of fat-soluble vitamin levels in children with FH. Though children following a lipid-lowering diet have normal serum levels of fat-soluble vitamins, the alpha-tocopherol level does not appear to increase proportionately to the increase in cholesterol level. Treatment with resins may restore a normal alpha-tocopherol/lipid ratio.