Measurement of LDL-Cholesterol in Serum by New Enzymatic Method

Abstract

Low density Lipoprotein (LDL) plays a key role in causing and influencing the progression of atherosclerosis and coronary sclerosis in particular. The LDLs are derived from Very Low Density Lipoproteins (VLDLs). The elimination of LDL from plasma takes place mainly by the liver parenchymal cells via specific LDL receptors. The LDL-cholesterol value is the most powerful clinical predictor among all of the individual parameters with respect to coronary atherosclerosis. Therefore, therapies focusing on lipid reduction primarily target the reduction of LDL-cholesterol which is then expressed in prevention of atherosclerosis. This new enzymatic automated method for direct determination of LDL-cholesterol in serum had good precision and accuracy. Reproducibility was determined daily using control precinorm^® L in an internal protocol (n = 20), within-run CV = 0.856%, and between-run CV = 2.6%. The comparison of the LDL-C level by enzymatic assayed with the calculated LDL-C using the HDL-C determination by enzymatic assayed and by precipitation, showed a good correlation (r = 0.989, Y = 0.966X - 7.255, n = 188 and r = 0.977, Y = 0.957X - 7.049, n = 188). The normal range of LDL-C concentration in serum by this enzymatic method was 57.47 - 221.39 mg/dl. Thus, a normal level of LDL-C should be < 200 mg/dl for good warning. A level > 200 mg/dl warns the doctors that the patient has a high risk of coronary atherosclerosis.