Cholesterol

LDL cholesterol

Low-density lipoprotein cholesterol (LDL-C) has been shown to be strongly associated with the development of atherosclerosis, Cardiovascular Heart Disease (CHD) and events in patients with established CHD (history of angina pectoris, MI etc.). This applies to women as well as men, but in women the general level of CHD risk is lower.¹ A 10% increase in LDL-C is associated with an approximate 20% increase in risk for CHD.¹

Most of the cholesterol present in plasma is found in LDL particles. LDL particles however vary in size with the amount of cholesterol they contain. The smaller particles contain less cholesterol per particle and, hence, are denser than the larger particles. Smaller, denser LDL particles are more atherogenic than larger, buoyant particles.²

The association between LDL-C and the risk of CHD events is considerably increased by other risk factors, such as low HDL-C, smoking, hypertension, diabetes and the metabolic syndrome.¹

HDL cholesterol

There is a strong inverse association between plasma HDL-C concentrationand the risk of CHD; therefore, HDL-C has a protective effect. This has been shown in both patients with CHD and in asymptomatic subjects, in men and women, and is independent of LDL-C and other risk factors. A low level (<40 mg/dL, 1.0 mmol/L) increases risk and a higher level (≥60 mg/dL, 1.6 mmol/L) can be considered a protective factor.¹ Concentrations of HDL-C tend to be low when triglycerides are high. It is thought that HDL-C goal should be higher for women than that for men.

Low concentrations of HDL-C are also associated with an atherogenic lifestyle, as HDL-C is lowered by smoking, obesity and physical inactivity.³

A combination of plasma triglycerides >2 mmol/L (180 mg/dL) and HDL-C <1 mmol/L (40 mg/dL) predicts a high risk of CHD, in particular if the total cholesterol to HDL-C ratio is greater than 5.¹ ApoA-I is the major apolipoprotein in HDL and an elevated ApoA-I is linked to reduced CVD risk.²

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References
1. Wood D et al, for the Joint European Committee, Second Task Force of European and other Societies. Atherosclerosis 1998;140:199–270.
2. In: Fast Facts - Hyperlipidaemia. Eds Durrington P, Sniderman A. Health Press Ltd, Oxford, Second Edition, 2002. 7–12.  
3. Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. JAMA 2001:285;2486–2497.

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