Comparison of seven different reagents of peroxidase method for small and dense low density lipoprotein cholesterol (sdLDL-C) measurement.

BACKGROUND: We validated the performance of seven different reagents of peroxidase method for sdLDL-C in two automatic analyzers that are common in Chinese laboratories. METHODS: Seven commercially available sdLDL-C assays were analyzed with the Beckman AU5400 and Mindray BS2000 automatic analyzers. A total of 336 blood samples were collected and the reference interval was also validated in 298 apparently healthy individuals. Serum samples were used for method comparison of precision, recovery, lower limit of detection, comparison and concurrence analysis, as well as reference interval for the Mindray reagent. RESULTS: The repeatability CV% of the seven sdLDL-C assays were 0.81%~3.66% for Mindray BS2000 and 0.76%~3.91% for Beckman AU5400, while Total CVs for Mindray BS2000 sdLDL-C assay were 1.34%~4.81%, and that of Beckman AU5400 were 2.25%~10.33%. The measured recovery rates of sdLDL-C assays were within the allowable ±10% deviation range. There was no obvious difference between the reagents in the lower limit detection. There was a difference between the validation results of the reference range and the manufacturer's.BSBE, Mindray, and Dongou had a high degree of association with DENKA SEIKEN on Mindray BS2000, while BSBE, Mindray, Dongou and Merit Choice had a high degree of association with DENKA SEIKEN on Beckman AU5400. Passing-Bablok regression showed excellent linear correlation between BSBE and Mindray and DENKA SEIKEN and on Beckman AU5400. CONCLUSIONS: Our results indicate that the basic performance can meet the testing requirements, but the comparability between them is still insufficient.

Small dense low-density lipoprotein cholesterol and sdLDL-C/LDL-C ratio associate with carotid atherosclerotic plaque / 中华检验医学杂志

Objective To explore the association between carotid artery plaque and small dense low-density lipoprotein cholesterol(sdLDL-C)concentrations as well as the probability of sdLDL-C and sdLDL-C/LDL-C ratio as biomarkers of human carotid atherosclerotic plaque.Methods 174 subjects in physical examination center of An Zhen Hospital from November 2015 to February 2016 were enrolled one by one as a cross-sectional study.All subjects were divided into carotid IMT abnormal group(n=92)and control group(n=82)according to carotid ultrasound.According to the thickness of IMT characterized by carotid ultrasound,subjects were divided into the thickened IMT group(n=32), plaques group(n=60), and plaques group were divided into single plaque group(n=33)and multiple plaques group(n=27).Body Mass Index(BMI), fasting serum sdLDL-C, triglyceride(TG), LDL-C and high-density lipoprotein cholesterol(HDL-C)concentrations were measured.Pearson′s and Spearman correlation coefficient analyses and logistic regression analyses were used to examine the relationships between carotid atherosclerotic plaque,sdLDL-C values,and other clinical variables.Area under curve(AUC)was calculated to determine the diagnostic value of sdLDL-C and sdLDL-C/LDL-C ratio in subjects with carotid atherosclerotic plaque. Results Levels of sdLDL-C(1.02 ±0.42 vs.0.97 ±0.46 vs.0.61 ±0.29, F=21.07, P<0.001)and sdLDL-C /LDL-C(0.34 ±0.17 vs.0.34 ±0.17 vs.0.21 ±0.09,F=16.34,P<0.001)in the thickened IMT group and the plaques group were higher than those of the control group).Even in individuals considered to be at low LDL-C(<2.59 mmol/L)level,sdLDL-C(0.94 ±0.41 vs.0.56 ±0.25,t=4.00, P<0.01)and sdLDL-C/LDL-C ratio(0.43 ±0.19 vs.0.24 ±0.08,t=4.45,P<0.01)remained higher in the carotid abnormal group than those in the control group.Age and sdLDL-C were the independent risk factors of carotid artery plaque.AUC of receiver operator characteristic curve(ROC)for serum sdLDL-C and sdLDL-C/LDL-C ratio were 0.882(95% CI:0.819-0.945, P<0.01)and 0.830(95% CI:0.747-0.914,P<0.01)to determine the multiple carotid atherosclerotic plaque,and the cut-off level were 0.90 mmol/L(sensitivity,88.0%;specificity,79.3%)and 0.30(sensitivity,84.0%;specificity,74.5%). Conclusions Carotid atherosclerotic plaque has a close relationship with sdLDL-C concentrations.sdLDL-C and sdLDL-C/LDL-C ratio can be biomarkers when assessing subjects with a carotid atherosclerotic plaque.