Reference values for lipid profile in Iranian children and adolescents: the CASPIAN-V study

Background We aimed to develop the age- and sex-specific reference values for lipid profile of Iranian pediatric population. Methods Fasting lipid profiles of 3843 participants, aged 7 to 18 years, were extracted from a surveillance survey on Iranian children and adolescents living in 30 provinces across the country. Results The mean (SD) age of participants was 12.3(3.1) years, and 52.3% of them were boys. Significant differences were observed between genders comparing the levels of triglyceride (TG) (P = 0.04), total cholesterol (TC) (P = 0.02), low-density lipoprotein- cholesterol (LDL-C) (P = 0.01), and non-high-density lipoprotein cholesterol (non-HDL-C) (P = 0.03). In both genders, TG levels increased with age in the 75th and higher percentiles. Among boys, TC showed a decreasing trend at all percentiles and all age groups. In girls, TC levels increased with age at all percentiles except for the 75th and 90th percentiles. Among boys, the levels of LDL-C and HDL-C decreased with age in all percentiles. However, LDL-C and HDL-C concentrations increased up to the 50th percentile in girls and then decreased with age. The non-HDL-C level decreased in the 50th and higher percentiles among boys and in the 90th and 95th percentiles among girls. The TG/HDL-C ratio increased with age at all percentiles in boys. In girls, TG/HDL-C ratio increased with age in the 50th and higher percentiles. Conclusions Based on the observed differences, it seems necessary to determine age- and sex-specific cut-off values for lipid parameters of children and adolescents in different populations.