Association of low-density lipoprotein particle size distribution and cardiovascular risk factors in children M. KOJIMA, H. KANNO, Y. YAMAZAKI, S. KOYAMA, S. KANAZAWA & O. ARISAKA Department of Paediatrics, Dokkyo University School of Medicine, Tochigi, Japan Abstract Aim: The objective of this study was to investigate whether the presence of small, dense lipoproteins, which are thought to be related to the metabolic syndrome caused by insulin resistance, can be predicted by routine serum lipid profiling. Methods: The relationship between low-density lipoprotein (LDL) particle size and serum lipid levels was analysed in 284 school children (148 boys and 136 girls), aged 7 to 13 y old. LDL particle size was determined by gradient gel electrophoresis. Results: The LDL particle diameter was significantly correlated with the serum levels of high-density lipoprotein cholesterol (HDL-C) (r=70.437, p50.001) and triglycerides (TG) (r=70.432, p50.001), and with the atherogenic index (AI) [total cholesterol/ HDL-C] (r=70.450, p50.001), while only weak correlations were observed with the serum levels of total cholesterol, apolipoprotein A1 and apolipoprotein B. No significant relationship was observed between LDL particle diameter and the serum LDL-C level. Conclusion: The presence of small, dense LDL as a metabolic marker of lifestyle-related diseases in children seems to be reflected by a serum lipid profile characterized by an elevation in TG, a reduction in HDL-C, and a raised AI. Key Words: Insulin resistance, LDL particle diameter, small, dense LDL, HDL cholesterol, triglycerides Many longitudinal cohort studies have demonstrated that childhood obesity and serum lipid abnormalities, including hypercholesterolaemia, are predictive of the development of atherosclerosis and coronary artery disease/myocardial infarction, which can be attributed to long-standing lifestyle practices [1–4]. Although various risk factors for atherosclerosis have already been confirmed, more recent studies have shown that small, dense low-density lipoproteins (LDL) with particle diameters 5 25.5 nm contribute signifi- cantly to the pathogenesis of coronary artery disease [5–8]. LDL, containing apolipoprotein B (ApoB), is a set of heterogeneous particles varying in diameter from 21.0 to 29.0 nm, and in density from 1.019 to 1.063 g/ml. As LDL particles become smaller, the amount of cholesterol contained in them also decreases, with a relative increase in the proportion of ApoB. Since small, dense LDL particles have now come to be recognized as a metabolic marker of insulin resistance, detection of their presence in plasma may be useful for the prediction and screening of lifestyle-related dis- eases that appear to be associated with insulin resistance [9–11]. In recent years, the presence of small, dense LDL in serum has been the focus of much attention, but currently available data on LDL particle size in children is limited [12–17]. In this study, we measured the LDL particle diameter in a large number of schoolchildren and investigated the relationship between the LDL particle diameter and the presence of the various other known risk factors of atherosclerosis. The measurement of LDL particle diameter, however, is not routinely performed in the clinical setting. Therefore, we quan- tified the serum lipid levels by a general clinical laboratory test in schoolchildren and investigated the correlation between the various parameters of the lipid profile and a presence of small, dense LDL in signifi- cant amounts, which is now known to be associated with the development of lifestyle-related diseases. If parameters of the serum lipid profile could reflect the presence of small, dense LDL, even a routine clinical laboratory test in a regular physical check-up may be useful for the screening of lifestyle-related diseases and evaluation of the effects of therapeutic interventions in children to prevent these diseases. Correspondence: O. Arisaka, Department of Paediatrics, Dokkyo University School of Medicine, Mibu, Tochigi 321-0293, Japan. Tel: +81 282 86 1111. Fax: +81 282 86 7521. E-mail: arisaka@dokkyomed.ac.jp (Received 2 February 2004; accepted 14 June 2004) Acta Pædiatrica, 2005; 94: 281–286 ISSN 0803-5253 print/ISSN 1651-2227 online # 2005 Taylor & Francis Group Ltd DOI: 10.1080/08035250410022585