The basics: Hyperlipidaemia

Dr Julian Spinks explains the risk factor measurement and treatment of hyperlipidaemia.

Hyperlipidaemia is the presence of elevated plasma concentrations of lipids including cholesterol, triglycerides and lipoproteins.

It is an important modifiable risk factor for cardiovascular disease (CVD).

The UK has among the highest levels of cholesterol in the world and most of the population has higher than recommended blood lipids.

Some 620,000 people in the UK have either familial hypercholesterolaemia or familial combined hyperlipidaemia.

These inherited disorders of lipid metabolism carry high risk of premature cardiovascular death if they are left untreated.

Clinical presentation
Only a minority of hyperlipidaemia is discovered when a patient attends with symptoms. The most common of these are tendon xanthomas, xanthelasma and premature corneal arcus.

It is more common for patients to attend with concerns about familial CVD.

The high prevalence and risks associated with hyperlipidaemia make screening worthwhile.

The Joint British Society guidelines recommend opportunistic screening of people with no history of cardiovascular disease as they reach 40 years and at five-year intervals.

It is possible to prioritise patients for assessment using existing recorded risk factors for CVD including age, sex, smoking status, BP, total cholesterol and HDL cholesterol.

Patients under the age of 40 should be screened if they have a family history of premature CVD (MI or stroke in a male relative under 55 years or a female under 65 years) or if there is suspected familial hyperlipidaemia.

A non-fasting blood sample for total cholesterol and HDL cholesterol is sufficient for initial screening, however, a second fasting sample would be required prior to treatment for measurement of LDL and triglyceride levels.

Risk assessment
A total cholesterol of over 7.5mmol/l, and LDL over 4.9mmol/l raises the possibility of familial hyperlipidaemia.

A family history of premature CHD or high cholesterol increases the likelihood of this condition, while the presence of tendon xanthomas would confirm the diagnosis. In these cases, referral for specialist assessment is recommended.

In other cases, the lipid levels need to be considered in the light of other cardiovascular risk factors. The most widely used method is the Framingham equation, which results in 10-year CHD and CVD risks.

Framingham does not take into account family history or ethnicity. The initial result should be multiplied by 1.5 if there is a first-degree relative with premature CHD and by up to two if there are multiple relatives affected. South Asian men should have their risk multiplied by 1.4.

However, an alternative risk calculator is QRISK. This is considered to produce a more accurate risk assessment for UK patients, and is currently being considered by NICE.

Patients with existing CVD and diabetic patients with hypertension, or poor glycaemic control should be treated.

Before starting treatment, secondary causes of hyperlipidaemia should be identified and treated. These include hypothyroidism, hepatic and renal disease, alcohol abuse, pregnancy and multiple myeloma.

Some drugs also raise lipids, including beta-blockers, high-dose thiazides, atypical antipsychotics, corticosteroids and oral contraceptives.

All patients should be offered lifestyle advice. Smokers should be advised to stop and high alcohol consumption reduced.

Exercise is beneficial, and 30 minutes of exercise, five times a week is recommended.

Patients should lose weight and follow a low-fat diet where saturated fats is less than 10 per cent. Five portions of fruit and vegetables a day and two portions of oily fish a week are also beneficial.

Food containing plant stanols can reduce cholesterol but there is insufficient evidence of cardiovascular benefit to recommend them.

First-line drug therapy is with a statin. Simvastatin 40mg or an equivalent is recommended for initial treatment. Use of high-dosage regimens for primary prevention is not proven.

The Joint British Societies recommend a target of <4mmol/l total cholesterol (or a reduction of 25 per cent) or <2mmol/l LDL (or a 30 per cent reduction).

Statins interact with a number of other medications and can have side-effects including myositis, myalgia and (rarely) rhabdomyolysis. If there is muscle pain and a markedly raised creatine kinase, the statin should be stopped.

A baseline LFT is required before treatment to be repeated at six months and 12 months. Transaminase levels over three times baseline may require dosage reduction or the treatment to be stopped.

Other drugs can be used to replace or augment statins if these are not tolerated or give insufficient control.

These include ezetimide, fibrates, nicotinic acid and ion-exchange resins. None is recommended for first-line use.

Dr Spinks is GP in Strood, Kent

Key points

  • Hyperlipidaemia is an important modifiable risk factor for CVD.
  • Screening plays an important role in its detection.
  • A total cholesterol >7.5mmol/l or an LDL >4.9mmol/l may indicate familial hyperlipidaemia.
  • Use a Framingham or QRISK calculation to determine CVD risk and treat those with a 10-year risk over 20 per cent.
  • Lifestyle modification and statins are the first-line therapy.

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