Answer
About 60-70% of cholesterol in the body is carried as low-density lipoprotein cholesterol (LDL-C) in the blood.
The standard lipid profile, as recommended by the ATP III, consists of direct measurement of total cholesterol, HDL-C, and triglycerides, with a calculated LDL-C, obtained after a 9-hour to 12-hour fast. The Friedewald formula used to calculate the LDL level in the blood is as follows:
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LDL = Total cholesterol − HDL − (Triglycerides/5)
Lipoproteins are required for the transportation of cholesterol ,which in turn is required for the biosynthesis of bile acids, steroid hormones, and vitamin D.
Two main sources of cholesterol exist: One is dietary intake and the other is endogenous hepatic production.
Metabolism of ingested cholesterol yields very–low-density lipoprotein (VLDL) and intermediate-density lipoprotein (IDL). Further metabolism of the VLDL results in the cholesterol rich LDL, which is the key ingredient for the development of an atherosclerotic plaque.
