Hypercholesterolemia is a common dyslipidemia that leads to atherosclerosis. It is proved that early stages of atherosclerosis begins in early stages of life. In several studies, widespread prevalence of dyslipidemia in children is reported. So, assessment of lipid profile in children and adolescence is necessary for early diagnosis of dyslipidemia. Laboratory methods for measuring LDL are not available and economical. So, in some laboratories Friedwald method is used to determine LDL level. But, the preciseness of this method is not acceptable. Further, the preciseness of this method was not assayed in children and adolescence. So, it seems that assaying the preciseness of different methods is necessary. The methodology of this work is on the basis of findings of the Caspian V study. This study was conducted in 30 provinces of Iran during 2015. The population of this work was rural and urban students aged 7–18 years old. The level of total cholesterol (TC), HDL, LDL, and TG were measured using laboratory methods. The average and variances values were determined for each group of data using SPSS. Further, LDL values were calculated with a new formula introduced in this work. A comparison was made between the new formula and the other methods. In the present study, we found that compare to four common formulas, Friedwald was the best equation to estimate LDL-C concentrations in Iranian children and adolescents and the new formula was the next accurate equation. The strongest correlation between Friedwald and the new equation was found for those with 15–18 years old. Considering the cut-off points of TG (100 mg/dL), we observed the strongest correlation between Friedwald equation and direct assay and the weakest one was for Ahmadi formula in subjects with either greater or lower TG concentrations. Furthermore, we found that Anandraja equation had the most sensitivity (89.5%), while the most specificity was dedicated to the new formula (98.9%).

中文翻译：

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在伊朗儿童和青少年中使用直接测定法比较LDL-C计算的通用方程式并开发出新的公式：CASPIAN V研究。

高胆固醇血症是导致动脉粥样硬化的常见血脂异常。事实证明，动脉粥样硬化的早期阶段始于生命的早期阶段。在一些研究中，报道了儿童血脂异常的普遍流行。因此，评估儿童和青春期的血脂状况对于血脂异常的早期诊断是必要的。测量LDL的实验室方法尚不经济。因此，在某些实验室中，使用Friedwald方法来确定LDL水平。但是，这种方法的准确性是不可接受的。此外，未在儿童和青春期测定该方法的准确性。因此，似乎有必要分析不同方法的准确性。这项工作的方法是基于里海五世研究的结果。这项研究于2015年在伊朗的30个省进行。这项工作的人群是7至18岁的农村和城市学生。使用实验室方法测量总胆固醇（TC），HDL，LDL和TG的水平。使用SPSS确定每组数据的平均值和方差值。此外，LDL值是通过这项工作中引入的新公式来计算的。在新公式和其他方法之间进行了比较。在本研究中，我们发现与四个常用公式相比，Friedwald是估算伊朗儿童和青少年中LDL-C浓度的最佳公式，而新公式是下一个精确公式。对于15至18岁的人群，发现Friedwald与新方程之间的最强相关性。考虑到TG的临界点（100 mg / dL），我们观察到Friedwald方程与直接测定之间的相关性最强，而对于TG浓度较高或较低的受试者，Ahmadi公式的相关性最弱。此外，我们发现Anandraja方程具有最高的灵敏度（89.5％），而对新配方的特异性最高（98.9％）。