Measurement of HDL-cholesterol in serum by a new enzymatic method.

High density lipoprotein (HDL) are responsible for the reverse transport of cholesterol from the peripheral cells to the liver. Here, cholesterol is metabolised. Monitoring of HDL-C in serum is of clinical importance since an inverse correlation exists between serum HDL-C concentrations and the risk of atheroselerotic disease. Elevated HDL-C concentrations are protective against coronary heart disease. In this study, an automated enzymatic method for the direct determination of HDL-C in serum was found to have good precision and accuracy. Reproducibility was determined daily using control precinorm? L in an internal protocol (n=20), within-run CV = 1.3% and between-day CV = 2.013%. The comparison of the HDL-C enzymatic assay with HDL-C precipitating agent was good with a correlation coefficient r = 0.965, Y = 1.981+ 0.959X, n =172. The normal range of HDL-C concentration in serum by this enzymatic method was 36.16 -86.08 mg./dl. Thus, a HDL-C level of over 35 mg/dl., shows the risk is not high and is protective against coronary heart disease.

Measurement of LDL-cholesterol in serum by new enzymatic method.

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 determinaton 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.