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  • br Acknowledgments br Introduction Cholesterol is


    Introduction Cholesterol is an essential lipid for the development, growth, and wellbeing of humans. In newborn children, cord blood cholesterol concentration is 1.5 mmol/l, on average [[1], [2], [3], [4]]. During the first year of life, cholesterol concentration in serum increases to about 4–5 mmol/l [5], a level that remains throughout the childhood [6]. Serum cholesterol concentration, as well as cholesterol metabolism, is regulated by genetic, dietary, hormonal, and lifestyle factors, e.g., in newborns with heterozygous familial hypercholesterolemia, the concentration of cord blood cholesterol is elevated up to about 2.4 mmol/l, and at the age of 1 year, serum cholesterol concentration is about 8 mmol/l [2]. Already in childhood and adolescence, elevated serum and LDL cholesterol concentration can lead to atherosclerotic changes in arterial wall [7]. In addition to LDL cholesterol, the whole-body cholesterol metabolism may have a role in the development of atherosclerosis. This was suggested in adult cohorts in which high cholesterol R406 free base efficiency increased the risk of coronary events regardless of LDL cholesterol concentration [[8], [9], [10], [11]]. The growth and development in childhood and adolescence question the whole-body cholesterol metabolism, which may vary between different ages. To our knowledge, there is only a limited number of studies on limited age periods dealing with cholesterol metabolism in healthy children and adolescents [[1], [2], [3], [4],[12], [13], [14]], and there are no studies reaching all age groups from newborn to adolescence. Thus, there is no information on whether the metabolic profile of cholesterol differs between age groups or gender in children and adolescents. Therefore, the aim of this study was to evaluate cholesterol metabolism in healthy children from 0 to 15 years of age by analysing serum non-cholesterol sterols, which in general are used as biomarkers of cholesterol synthesis and cholesterol absorption [[15], [16], [17], [18], [19]].
    Patients and methods
    Results The study population consisted of 96 children and adolescents. Thirty-nine subjects were girls and 57 were boys (Table 1). The mean age of the study population was 6.6 ± 0.5 (SE) years ranging from 0.10 to 15.94 years, and there was no difference between girls and boys. Weight was available from 34 girls and 55 boys, but height was measured only in 6 girls and 21 boys, so that body mass index was not calculated. Weight ranged from 6.2 kg to 64.0 kg in girls and from 4.4 to 76.7 kg in boys, respectively. The mean serum cholesterol concentration was 3.83 ± 0.07 mmol/l in the whole study population ranging from 2.52 to 5.01 mmol/l in the girls and from 2.21 to 5.47 mmol/l in the boys, with no difference between the genders. The main reasons for the day-surgery were: corrections of umbilical or inguinal hernia or testis retention, removal of nevus or other skin, subcutaneous, cartilage, or bone lesions, all benign in histology, arthroscopy, different endoscopies, or circumcision. The study population was divided into 5-year age groups 1–5 (n = 37), 6–10 (n = 24), and 11–15 years (n = 21) (Table 1). Less than 1-year old (n = 14) subjects were left as their own group because some of the serum non-cholesterol sterols behaved differently in the first year of life compared with the other age groups. According to power analysis based on previous data [2], with an α level of 0.05 (two-sided) and statistical power of 0.80, the required minimal study population per age group should be 12, so that each group fulfilled the criteria of optimal size. In the age group 1–5 years, the boys were heavier than the girls (17.9 ± 0.8 kg vs. 14.5 ± 0.7 kg, p = 0.008), but in the other age groups there was no gender difference in weight. Serum cholesterol concentration was higher in the girls than in the boys in the age group <1 year (4.14 ± 0.28 vs. 3.18 ± 0.19 mmol/l, p = 0.047), but in the other age groups neither serum cholesterol nor non-cholesterol sterols differed between the genders.