Hyperlipidemia: Overview and Risk Factors

Hyperlipidemia is characterized by elevated concentrations of circulating lipids, increasing the risk of atherosclerosis and other serious conditions. Specific classes of hyperlipidemia include hyperlipoproteinemia, elevated very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) levels, hypercholesterolemia (elevated cholesterol levels), and hypertriglyceridemia (elevated triglyceride levels).

Hyperlipidemia is typically asymptomatic and is frequently detected during routine screening. Occasionally, xanthelasmas and xanthomas are present. These are fatty deposits under the skin surface commonly found in patients with genetic disorders such as familial hypercholesterolemia.

Hyperlipidemia often results from delayed or defective clearance, or overproduction of VLDL by the liver, which is subsequently transformed into LDL. Familial hypercholesterolemia involves defective hepatic and nonhepatic LDL receptors. Excess intake of saturated fats increases the liver's production of VLDL and triglycerides via a molecular mechanism involving protein activators.¹ Saturated fats are found in animal products, such as meat, whole milk dairy products (milk, cream, cheese), and butter, and tropical oils (palm, palm kernel, and coconut).

High concentrations of total and LDL cholesterol and low levels of high-density lipoprotein (HDL) cholesterol predict cardiovascular risk in both men and women. High triglyceride levels have been associated with greater risk in women only.² The risk of cardiovascular disease increases by an average of 2% for each corresponding 1% rise in total cholesterol.

Risk Factors

Although hyperlipidemia is a frequent finding in all demographic groups that follow Western diets, it occurs somewhat more commonly in men. Additional risk factors include:

• Family history
• Diets high in total fat, saturated fat, and cholesterol (see Nutritional Considerations)
• Diabetes mellitus and metabolic syndrome: Hyperinsulinemia is associated with low HDL levels and hypertriglyceridemia.
• Chronic renal failure is associated with hypertriglyceridemia.
• Nephrotic syndrome: Decreased vascular oncotic pressure due to proteinuria leads to increased lipoprotein production by the liver.
• Hypothyroidism
• Hypopituitarism.
• Obesity: Obesity is associated with increased total cholesterol, LDL, VLDL, and triglycerides, as well as with decreased levels of HDL.
• Physical inactivity
• Alcoholism
• Steroid use
• Oral contraceptives
• Smoking: Cigarette smoking lowers HDL levels and is an independent risk factor for cardiovascular disease.