8. TYPICAL DERANGEMENTS OF LIPID METABOLISM. ATHEROSCLEROSIS

Typical disorders of lipid metabolism include:

•  hyperlipidemia;

•  hypolipidemia;

•  dyslipidemia;

•  obesity;

•  lipodystrophy, wasting, cachexia;

•  lipidoses.

HYPERLIPIDEMIA

Hyperlipidemia is an increase in the plasma lipids concentration above 8 g/L.

Types of hyperlipoproteinemia (Fredrickson, 1967):

Lipoproteins can be classified by their ability to cause atherosclerosis (fig. 8).

Mechanisms of hyperlipoproteinemia:

•  Abnormal structure of receptors for lipoproteins on the cell's surface (e.g. familial hypercholesterolemia).

•  Defective structure or synthesis of apoproteins (e.g. defective synthesis of apo-B100, apo-E, apo-CII).

Fig. 8

•  Deficient activity of plasma lipoproteinlipase.

•  Increased mobilization of lipids from the lipid stores.

HYPOLIPIDEMIA

Hypolipidemia is a decrease in the plasma lipids concentration below 4 g/L. Mechanisms of hypolipoproteinemia.

•  Abnormal synthesis of apo-B.

•  Defective formation of VLDL (the absence of the microsomal triglyceride transfer protein). For example, abetalipoproteinemia.

•  Abnormal synthesis of apo-A (e.g. hypoalphalipoproteinemia - Tangier's disease).

DYSLIPIDEMIA

Dyslipidemia is manifested as changes in the normal ratio between different classes of lipoproteins, or formation of abnormal lipoproteins.