Chapter 13: Plasma Lipids and Lipoproteins

Plasma Lipids and Lipoproteins details the chemical composition and physiological functions of major lipid classes, including fatty acids, triglycerides, phospholipids, and cholesterol, while emphasizing their clinical significance in the development of atherosclerosis and coronary heart disease. Because lipids are insoluble in water, they are transported via specialized protein complexes known as lipoproteins, which are categorized by density into chylomicrons, very low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL). The discussion covers critical metabolic pathways, such as the exogenous and endogenous transport of lipids and the cardioprotective process of reverse cholesterol transport facilitated by HDL. A major portion of the chapter is dedicated to the classification and diagnosis of lipid disorders, distinguishing between primary genetic hyperlipidaemias—like familial hypercholesterolaemia, often caused by LDL receptor defects—and secondary causes such as diabetes, obesity, and hypothyroidism. Clinical investigation techniques, including the Fredrickson classification and the Friedewald equation for calculating LDL cholesterol, are explained alongside therapeutic management strategies. These interventions range from dietary modifications and lifestyle changes to pharmacological treatments using HMG-CoA reductase inhibitors (statins), fibrates, and bile acid sequestrants to manage cardiovascular risk and prevent acute complications like pancreatitis.