Tighe Dennis A, Ockene Ira S, Reed George, Nicolosi Robert
Department of Medicine, Division of Cardiovascular Medicine, University of Massachusetts Medical School, 55 Lake Avenue, North, Worcester, MA 01655, USA.
Clin Chim Acta. 2006 Mar;365(1-2):236-42. doi: 10.1016/j.cca.2005.08.026. Epub 2005 Nov 2.
Increased low density lipoprotein cholesterol (LDL-C) is an established risk factor for the development of coronary artery disease (CAD). Recent guidelines detail specific LDL-C cutpoints for therapeutic goals. In practice, LDL-C is usually derived from the Friedewald formula (FF). This calculation is known to be inaccurate with serum triglyceride (TG) concentrations >4.52 mmol/l, however, its accuracy among relatively healthy patient cohorts with TG concentrations < or =4.52 mmol/l is less well studied.
We studied 661 ambulatory adults with TG concentrations < or =4.52 mmol/l and no overt CAD. Fasting venous lipid panels were obtained. LDL-C was calculated from the FF and also directly measured with the LipiDirect Magnetic LDL assay. Linear regression and paired t-test analyses were performed.
Calculated and directly measured LDL-C concentrations were significantly different (4.26+/-0.88 vs. 4.83+/-1.06 mmol/l respectively, p<0.0001). In 93% of measurements directly measured LDL-C exceeded calculated LDL-C. Although calculated and directly measured LDL-C concentrations were related (R=0.90), the discrepancy between them increased linearly with increasing TG concentrations (R=0.67) and clinically important differences existed at normal or slightly increased TG concentrations. Concordant results for NCEP ATP-III risk categories were present for only 48.1% of samples.
Significant differences between calculated and directly measured LDL-C using the LipiDirect Magnetic LDL assay exist in healthy subjects with TG < or =4.52 mmol/l. These differences are linearly related to TG concentrations and occur frequently at relatively low TG concentrations.
低密度脂蛋白胆固醇（LDL-C）升高是冠状动脉疾病（CAD）发生的既定危险因素。近期指南详细说明了治疗目标的特定LDL-C切点。在实践中，LDL-C通常由Friedewald公式（FF）得出。已知当血清甘油三酯（TG）浓度>4.52 mmol/l时，该计算不准确，然而，其在TG浓度≤4.52 mmol/l的相对健康患者队列中的准确性研究较少。
我们研究了661名TG浓度≤4.52 mmol/l且无明显CAD的门诊成年人。获取空腹静脉血脂检测结果。LDL-C通过FF计算得出，并使用LipiDirect磁性LDL检测法直接测量。进行线性回归和配对t检验分析。
计算得出的和直接测量的LDL-C浓度存在显著差异（分别为4.26±0.88 vs. 4.83±1.06 mmol/l，p<0.0001）。在93%的测量中，直接测量的LDL-C超过了计算得出的LDL-C。尽管计算得出的和直接测量的LDL-C浓度相关（R=0.90），但它们之间的差异随TG浓度升高呈线性增加（R=0.67），且在正常或轻度升高的TG浓度下存在临床重要差异。仅48.1%的样本NCEP ATP-III风险类别结果一致。
在TG≤4.52 mmol/l的健康受试者中，使用LipiDirect磁性LDL检测法计算得出的和直接测量的LDL-C之间存在显著差异。这些差异与TG浓度呈线性相关，且在相对较低的TG浓度下频繁出现。
