CHOLESTEROL, RAISED

Cholesterol is a fatty substance essential to cell membranes and the synthesis of bile salts and hormones. It is synthesised mostly by the liver. Dietary intake plays a lesser role in overall cholesterol levels than previously thought. Hyperlipidaemia is the term used to denote raised serum levels of one or more of total cholesterol (TChol), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TGs).

Dyslipidaemia is the term that also includes low levels of high-density lipoprotein cholesterol (HDL). In simple terms, LDL-C increases the risk of cardiovascular disease (1% increased risk of coronary heart disease (CHD) for each 1% increase in LDL-C) and HDL-C protects against the development of atherosclerosis and thus reduces the risk of CHD (2-3% reduction for each 1% increase in HDL-C). TGs are an independent risk factor for CHD. Desirable levels: 

• TC ≤5.0 mmol/l
• LDL cholesterol (fasting) ≤3.0 mmol/l
• HDL cholesterol (fasting) ≥1.2 mmol/l
• TC/HDL ratio ≤4.5
• TGs

Specific targets for TC and LDL-C, previously suggested for secondary prevention of cardiovascular disease (i.e. TC of 4mmol/l or less and LDL-C of 2mmol/l or less) are no longer used: instead, the recommended approach is to reduce non-HDL-C by 40% or more. 

Cholesterol levels can be reduced by lifestyle measures and drug therapy. See also Coronary heart disease. Familial hyperlipidaemia (FH) An inherited disorder characterised by very high cholesterol levels (>7.5 mmol/l) and a consequent high risk of cardiovascular disease. Early diagnosis is important, as it allows patients to be offered cholesterol-lowering medication and advice on life-style measures.