8. TYPICAL DISORDERS 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. Atherogeneicity of lipoproteins

• 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.

OBESITY

Obesity can be defined as an increase in body weight above the standard values, designated as «ideal weight», by 20% or more due to accumulation of fat in the adipose tissue.

Body mass index (BMI) = weight in kg / height in m².

Good weight: BMI = 20-24.9 kg/m².

Overweight: BMI = 25-30 kg/m².

Obesity: BMI >30 kg/m².

Types of obesity based on their pathogenesis.