Objective To investigate the distribution characteristics of serum small dense low density lipoprotein-cholesterol (sdLDL-C) levels in healthy normolipidemia and hyperlipidemia and analyze the correlation between sdLDL-C and other serum lipids.Methods Totally 1012 normolipidemic subjects (18 93 years old,503 male,509 females) were grouped according to gender and age (18 -29,30 -69 and ≥70 years old).And 433 hyperlipidemic subjects (23 -90 years) were divided into the following 3 groups based on fasting triglyceride (TG) and low density lipoprotein-cholesterol (LDL-C)levels:hypertriglyceridemia (n =165 ),high-LDL-C ( n =129) and combined hyperlipidemia ( n =139 ).The sdLDL-C and other serum lipids were measured by Olympus AU2700 automatic analyzer.Analysis of Variance and Kruskal-Wallis H test was used for statistical analysis.Results The distribution of the sdLDL-C levels in normolipidemic subjects was near normal distribution.The sdLDL-C levels had differences in gender and age.In the 18 -29 and 30 -69 years old group,the mean values of sdLDL-C were significantly higher in males than in females [ (0.55 -0.21 ) mmol/L vs (0.47 ±0.22) mmol/L,t =2.212,P =0.028 and (0.66±0.28) mmol/L vs (0.62±0.25) mmol/L,t =2.121,P=0.034].In the ≥70 years old group,the difference of sdLDL-C levels in gender was not statistically significant [ male ( 0.54 ± 0.21 )mmol/L vs female (0.54 ± 0.22 ) mmol/L,t =0.022,P =0.982] ; the mean value was ( 0.54 ± 0.22 ) mmol/L The hyperlipidemic subjects had conspicuous higher levels of sdLDL-C compared with normolipidemia [ ( 1.25 ±0.44) mmol/L vs (0.60 ±0.26) mmol/L,t =29.306,P ＜0.001 ].Among all of groups,the combined hyperlipidemia group had the highest sdLDL-C level [ ( 1.52 ± 0.49) mmol/L,F =525.66,P ＜0.001 ] ; the hypertriglyceridemia group had the highest sdLDL-C/LDL -C level (0.47 ±0.12,F =287.93,P ＜0.001 ) and the high-LDL-C group had the highest level of non-sdLDL-C [LDL-C subtract sdLDL-C,(2.71 ± 0.52) mmol/L.F =336.32,P ＜ 0.001 ].The sdLDL-C showed a good positive correlation with TC,TG,LDL-C,ApoB and BMI ( rs =0.66,0.68,0.65,0.79 and 0.27,P ＜ 0.001 ),and negative correlation with HDL-C and ApoA1 ( rt =- 0.42 and - 0.37,P ＜ 0.001 ).Based on partial correlative analysis,sdLDL-C showed a different correlation with TG,LDL-C and TC ( r =0.42,0.28 and 0.15,P ＜ 0.001 ).Conclusions LDL-C and TG are the important factors influencing the sdLDL-C levels.However,TG has greater effect than LDL-C.The sdLDL-C is an appropriate and good index to evaluate the small dense low density lipoprotein (sdLDL) mass and the overall situation of lipid metabolism.In order to make full use of sdLDL in the clinical treatment and health assessment,it is necessary to establish sdLDL-C reference intervals through the survey of distribution of sdLDL-C levels in different geographic areas.

Objective To study the serum small dense low density lipoprotein-cholesterol (sdLDL-C)concentration in patients with clinical and sub-clinical primary hypothyroidism,and to explore the clinical significance of serum sdLDL-C determination in pa-tients with hypothyroidism.Methods 60 patients with clinical hypothyroidism(clinical hypothyroidism group),96 cases with sub-clinical hypothyroidism(sub-clinical hypothyroidism group)and 132 normal subjects (normal group)were enrolled in the study. FT3,FT4,thyroid stimulating hormone (TSH),TG,TC,HDL-C,LDL-C,apolipoprotein AⅠ(ApoAⅠ),apolipoprotein B (ApoB), and sdLDL-C concentrations were measured.Analysis of Variance,Kruskal-Wallis H test and Spearman rank correlation analysis were used for statistical analysis.Results The concentration of sdLDL-C in sub-clinical hypothyroidism group was significantly higher than that in normal group (t=5.78,P <0.01),the concentration of sdLDL-C in clinical hypothyroidism group was signifi-cantly higher than that in sub-clinical hypothyroidism group(t=-2.88,P <0.01)and in normal group (t=6.68,P <0.01).There was statistically significant difference among groups (F =37.66,P <0.01).Correlation analysis showed that sdLDL-C in primary hypothyroidism patients was positively correlated with LgTSH (r =0.203,P =0.011 ),and negatively correlated with FT4 (r =-0.169,P =0.035).Conclusion The high concentration of sdLDL-C is a manifestation of dyslipidemia in primary hypothyroidism patients,and an important risk factor for atherosclerosis in primary hypothyroidism patients.

Objective To investigate the levels of small and dense low-density lipoprotein-cholesterol (sdLDL-C) and the influence of insulin therapy on lipid metabolism in type 2 diabetic patients.Methods The subjects were composed of a normal group (n =400,195 males and 205 females),and a type 2 diabetic patients group (n =193,108 males and 85 females) which was further divided into normal lipid (n =33),hypercholesterolemia (n =21,TC ≥ 5.18 mmol/L),hypertriglyceridemic (n =53,TG ≥ 1.7 mmol/L),combined hyperlipidemia (n =75),and low high-density lipoprotein-cholesterol(n=11,HDL-C＜ 1.04 mmol/L) subgroups.The pre-and post-treatment levels of sdLDL-C and the influence of insulin therapy on lipid metabolism in type 2 diabetic patients (n =122,70 males and 52 females) were compared.Serum concentrations of sdLDL-C (sdLDL-EX SEIKENreagent),triglyceride (TG),total cholesterol (TC),and fasting plasma glucose (FPG) were measured by automatic biochemical analyzer,fasting insulin and C-peptide were determined by chemiluminesence immunoassay,TG/HDL-C,sdLDL-C/ LDL-C,LDL-C/HDL-C,apoB/apoA Ⅰ,and other parameters were calculated.Results Compared with diabetic normal lipid group,the levels of sdLDL-C in hypercholesterolemia,hypertriglyceridemic,and combined hyperlipidemia subgroups were significantly higher(P＜0.05),the levels in combined hyperlipidemia subgroup were the highest.The levels of sdLDL-C in low high density lipoprotein cholesterol group showed no significantly difference (P＞0.05).While compared with normal group,the levels of sdLDL-C,TG,TC,LDL-C,ApoB,sdLDL-C/LDL-C,TC/HDL-C,TG/HDL-C,LDL-C/HDL-C,apoB/apoA Ⅰ,CRP,and HOMA-IR in type 2 diabetic patients were significantly higher(P＜0.05).Compared with pre-treatment group,the levels ofTG,TC,LDL-C,sdLDL-C,sdLDL-C/LDL,TC/HDL-C,TG/HDL-C,LDL-C/HDL-C,and apoB/apoA Ⅰ in post-treatment group were significantly lower(P ＜ 0.05).Conclusions sdLDL-C is the important indicator of lipid metabolism in type 2 diabetes,particularly in evaluating the changes in LDL particles.Insulin therapy is effective both in blood glucose control and improvement of dyslipidemia.Important information of clinical risk of dyslipidoses in type 2 diabetic patients provided by TG/HDL-C,LDL-C/HDL-C,sdLDL-C/LDL-C,and apoB/apoA Ⅰ ratios should be recognized and implemented in future clinical guidelines.