LDL Cholesterol

182

Lipids

LDL cholesterol

Serum or heparinised plasma

R1: 1 x 31.5 mL;
R2: 1 x 10.5 mL,
Ready for use

Instructions for Use  |  Safety Data Sheet

For professional use only.

Total cholesterol in humans is principally distributed between three major classes of lipoproteins: VLDL (very low-density lipoproteins), LDL (low density lipoproteins) and HDL (high density lipoproteins). An increase in the plasma levels of LDL cholesterol constitutes one of the major risk factors for the development of coronary heart disease (CHD). In humans, LDL are carriers which transport two thirds of the blood cholesterol, having an important role in the formation of aterosclerotic plaques. LDL catabolism takes place in the liver and peripheral tissues following interaction with specific highaffinity LDL receptors. The presence of these receptors has been demonstrated in most cells, although they are more numerous in certain types, e.g. adrenocortical cells in which LDL cholesterol acts as principle substrate for the synthesis of steroid hormones. A defect in the process of removal of LDL or the superposition of low-density lipoproteins, precursors of LDL, can cause an increased concentration of LDL in the serum. The precipitation method for the determination of LDL cholesterol is little used because the results are often inaccurate in the presence of high serum triglycerides levels. The concentration of LDL cholesterol is measured in the serum or plasma collected from the patient after fasting, taking three different parameters: total cholesterol, HDL cholesterol and total triglycerides. The accuracy of this formula is due to the fact that the serum levels of triglycerides are closely correlated to the VLDL concentrations. The LDL method is based on the selective solubilisation of LDL cholesterol by an ionic detergent and the interaction of some lipoprotein components (VLDL and chilomicrons).

LDL-L reagent is produced using a combination of detergents and phosphorous compounds that specifically bind HDL, VLDL, and CM (chylomicrons) but not LDL. This combination does not allow HDL, VLDL, and CM to react with CO (cholesterol Oxidase) and CE (Cholesterol Esterase) while LDL-cholesterol remains capable of reacting with both enzymes.
LDL (cholesterol ester) + H2O --(CE)--> Cholesterol + Fatty Acid
Free Cholesterol + O2 --(CO)--> Delta4 cholestenon + H2O2
2H2O2 + 4-AA + HDAOS --(POD)--> 4H2O + Quinone dye
The compound (Quinone dye) which forms is read at λ 578 nm, develops a colour, the intensity of which is proportional to the LDL concentration in the test sample.

Store at 2 - 8°C and protect from direct light. When correctly stored, the reagents are stable up to the expiry date reported on the label. A slight variation in the composition of the reagents may occur between batches, but this has no effect on the test results. After opening, the vial R1 and R2 are stable 30 days if recapped immediately and protected from contamination, evaporation, direct light and stored at correct temperature.

HDL/LDL cholesterol calibrator (R0300000009)
Normal control serum (R0400000006)
Pathological control serum (R0400000106)
Control Serum for Cholesterol HDL-LDL (R0400000300)