Lipid Panel

Measurement of the serum lipids and lipoproteins is useful in characterizing an individual’s risk of developing cardiovascular diseases (CVD) and in monitoring therapeutic interventions. Consensus-based guidelines for measurement and cut-points for interpretation have been provided by the National Cholesterol Education Program.

The circulating lipids are carried on lipoproteins. The LDL fraction, the major lipoprotein contributor to the development of atherosclerosis and for which treatment has been conclusively demonstrated to be effective, carries most of the circulating cholesterol in the blood. Total serum cholesterol has been measured for many years to quantify the total amount of lipoproteins as a convenient means of assessing CVD risk. However, some of the cholesterol is carried on HDL particles, which are antiatherogenic or inversely associated with risk of developing CVDs. Thus, quantitation of the major individual cholesterolcarrying lipoproteins, LDL and HDL, provides a better assessment of overall risk.

Triglycerides, the body’s major fuel, are carried into the blood stream on large lipoproteins called chylomicrons (CM). VLDL particles also carry triglycerides, primarily synthesized in the liver from excess fatty acids. In the circulation triglycerides are hydrolyzed and their fatty acids transported into peripheral cells leaving remnant particles, precursors to LDL. After an overnight fast, chylomicrons have generally been cleared from the circulation. Higher levels of triglycerides measured in a fasting specimen indicate impaired clearance or over-production, which may increase risk of developing CVD, making their measurement useful in characterizing metabolic disorders and overall risk.

The US National Heart, Lung and Blood Institute organized the National Cholesterol Education Program, which convened expert panels to develop clinical guidelines for classification and treatment of high cholesterol. The most recent recommendations, the Adult Treatment Panel III guidelines, base treatment decisions primarily on the LDL levels, calculated as part of the lipid panel after measurement of total cholesterol, HDL, and triglycerides. LDL cut-points of 100, 130, 160, and 190 mg/dL define optimal, near optimal, borderline high, high and very high risk categories. An HDL value below 40 mg/dL is low, considered to be a risk factor by the ATPIII, modifying the LDL treatment goal. An HDL value above 60 mg/dL is defined as high, considered desirable and a negative risk factor, subtracting from the total number of risk factors in selecting the appropriate treatment goal for LDL. For triglycerides, cut-points of 150, 200, and 500 mg/dL define normal, borderline-high, high, and very-high levels. Additionally, the calculated non-HDL cholesterol optimally should be < 130 mg/dL, with increased risk for cardiovascular disease associated with concentrations of 130 – 189 mg/dL, and high risk of CVD associated with values > 189 mg/dL.

The Piccolo Total Cholesterol and HDL assays have met the requirements for certification of accuracy and precision by the Cholesterol Reference Method Laboratory Network (CRMLN), which is coordinated by the Centers for Disease Control. The certification process evaluates the accuracy of method calibration and precision, helping to assure reliable classification of patients based on the NCEP cut-points.