To Measure Lipid Profile in Serum Sample
35
Lipids are organic substances relatively insoluble in water but soluble in organic
solvents and which are related to fatty acids. They are conc. storage form of energy
as well as structural components of biological membranes. The main lipids present in
plasma are cholesterol, triglycerides, phospholipids, and non-esterified fatty acids.
Lipids are transported in plasma and other body compartments in the form of
lipoproteins. The protein part of lipoprotein is called as apolipoproteins. Each
lipoprotein has a specific and relative constant composition of apolipoprotein. The
apolipoprotein plays an important role in lipid transport by activating or inhibiting
enzymes involved in lipid metabolism and recognizing cell membrane surface
receptors. The major lipoproteins are chylomicrons, very low-density lipoprotein
(VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL). A
lipid profile typically includes the estimation of total cholesterol, HDL, LDL,
VLDL, and triglycerides.
35.1 Sample Requirement...............................
Serum or plasma sample (fasting) can be used for lipid profile analysis. A random
sample can also be used if cholesterol alone has to be analyzed.
35.2 Total Cholesterol Estimation
35.2.1 Principle
Cholesterol esterase enzyme hydrolyzes cholesterol ester to free cholesterol and free
fatty acids. In the presence of oxygen, free cholesterol is oxidized by cholesterol
oxidase to form cholesten-4-ene-3-one and H 2 O2.The peroxidase enzyme splits
H 2 O 2 to water and oxygen; the oxygen thus formed oxidize phenol in presence of
#Springer Nature Singapore Pte Ltd. 2018
V. Kumar, K. D. Gill,Basic Concepts in Clinical Biochemistry: A Practical Guide,
https://doi.org/10.1007/978-981-10-8186-6_35
139