Cholesterol

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Cholesterol is a central molecule in embryogenesis, metabolic and membrane function. These pathways are illustrated at this link and involve not only its formation during steroid synthesis, but it is in man a precursor to bile acids and steroid hormones.

It is also obtained from dietary sources, but achievable dietary modifications do not make a large change in its plasma concentration. It is metabolised by cytochrome pathways (eg CYP7A, CYP11A, CYP27A1 and CYP46A1. It is a functional ligand in the Hedgehog signalling pathway of embryogenesis.

Measurement

A lipid profile usually measures total cholesterol (TC), cholesterol within high density lipoprotein (HDL) particles and triglyceride levels. Low density lipoprotein (LDL) cholesterol is usually derived from the figures above using the Friedewald formula where:[1]

LDL=TC-HDL-0.45*TG

The proportion of HDL relative to total cholesterol may be more important than the absolute numbers.

References