Lipids are insoluble in water and are therefore associated with serum lipoproteins to facilitate their transport in blood.

Figure %: A schema of lipid metabolism

The Fredrickson classification of hyperlipidemia describes six characteristic patterns of changes in the individual lipid moieties. HDL is not considered in this classification system. This is not a diagnostic classification and does not distinguish between primary and secondary hyperlipidemias or accurately predict risk of future coronary heart disease events.

Figure %: The Fredrickson classification of hyperlipidemia