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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).

Hyperlipidaemia Professional reference 

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.

NICE CG181 Cardiovascular disease: risk assessment and reduction, including lipid modification; 2014 (Updated 2016)
NICE CG71 Familial hypercholesterolaemia: Identification and management; 2008 (Updated 2017)
British Heart Foundation


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