Hypercholesterolemia

Hypercholesterolemia (literally: high blood cholesterol) is the presence of high levels of cholesterol in the blood. It is not a disease but a metabolic derangement that can be secondary to many diseases and can contribute to many forms of disease, most notably cardiovascular disease.

Table of contents

1 Signs and symptoms 2 Diagnosis 3 Classification 4 Treatment 4.1 Dissident views 4.2 Cholesterol and alternative medicine

Signs and symptoms

Elevated cholesterol does not lead to specific symptoms unless it has been longstanding. Some types of hypercholesterolaemia lead to specific physical findings: xanthoma (thickening of tendons due to accumulation of cholesterol), xanthalasma palpabrum (yellowish patches above the eyelids) and arcus senilis (white discoloration of the iris).

Longstanding elevated hypercholesterolemia leads to accelerated atherosclerosis; this can express itself in a number of cardiovascular diseases:

• Angina pectoris, leading to PTCA or CABG
• Myocardial infarction
• Transient ischemic attacks (TIA's)
• Cerebrovascular accidents/Strokes
• Peripheral artery disease (PAOD)

If the hypercholesterolemia is hereditary, there can be a family history of premature atherosclerosis, as well as familial occurrence of the signs mentioned above.

Diagnosis

When measuring cholesterol, it is important to measure its subfractions before drawing a conclusion on the cause of the problem. The subfractions are LDL, HDL and VLDL. VLDL levels are rarely measured directly, but are expressed in the levels of triglycerides (45% of triglycerides is composed of VLDL). Usually, even LDL is not measured directly but calculated from all the other fractions (total cholesterol minus HDL and VLDL); this method is called the Friedewald calculation.

There is a number of secondary causes for high cholesterol:

• Diabetes mellitus and syndrome X
• Kidney disease (nephrotic syndrome)
• Hypothyroidism

Classification

Classically, hypercholesterolemia is categorised by its appearance on lipoprotein electrophoresis by the Fredrickson classification.

• Type I: high chylomicrons
• Type II:
  • Type IIa: high LDL
  • Type IIb: high LDL and VLDL
• Type III: high chylomicrons and IDL (intermediate density lipoprotein)
• Type IV: high triglycerides
• Type V: very similar to Type I, but with high VLDL
• Non-classified forms are:
  • Hypo-alpha lipoproteinemia
  • Hypo-beta lipoproteinemia

Apart from Type II and Type IV, these disorders are very rare. Some have hereditary as well as acquired forms.

Treatment

The treatment depends on the type of hypercholesterolemia. Types IIa and IIb can be treated with diet, statins, fibrates, nicotinic acid, bile acid sequestrants, LDL apheresis and liver transplantation.

In patients without any other risk factors, moderate hypercholesterolemia is often not treated.

According to Framingham Heart Study, people with an age greater than 50 years have no increased overall mortality with either high or low serum cholesterol levels. There is, however, a correlation between falling cholesterol levels over the first 14 years and mortality over the following 18 years (11% overall and 14% CVD death rate increase per 1 mg/dL per year drop in cholesterol levels).

Dissident views

An increasing number of researchers are suggesting that the dietary risk factor for cardiovascular diseases is trans fatty acids, not saturated fats, as had been suggested by the Framingham Heart Study. More information needed here.

Some doctors, known as "the dissidents of the lipid hypothesis", claim that cholesterol itself is a healthy nutrient and that the whole "lipid hypothesis", which links cholesterol with heart disease and atherosclerosis, is incorrect. Some information can be found at the Weston A. Prince foundation, The International Network of Cholesterol Skeptics and The Cholesterol Myths.

Cholesterol and alternative medicine

A survey released in May 2004 by the National Center for Complementary and Alternative Medicine focused on who used (CAM), what was used, and why it was used in the United States by adults age 18 years and over during 2002. According to this recent survey, CAM was most often used to treat cholesterol by 1.1% of the adult population in the United States during 2002 ([1] table 3 on page 9). Consistent with previous studies, this study found that the majority of individuals (i.e., 54.9%) used CAM in conjunction with conventional medicine ( page 6).