Cholesterol tests and cardiovascular risk: how to interpret your numbers

Total cholesterol is the sum of cholesterol carried in several particle types. LDL cholesterol is often called the "bad" cholesterol because high levels promote fatty deposits in arteries. HDL cholesterol is often called "good" because it helps remove cholesterol from the blood. Non-HDL cholesterol, which is total minus HDL, captures all atherogenic particles and is increasingly used in UK practice. Triglycerides are blood fats that rise with alcohol, refined carbohydrate, obesity and diabetes. Targets depend on your overall risk.

A person with moderately raised cholesterol but low blood pressure, no diabetes and who does not smoke may have low overall risk, while someone with similar cholesterol, high blood pressure, diabetes and a family history may have high risk. Tools such as QRISK combine age, sex, ethnicity, blood pressure, cholesterol, smoking, diabetes, family history and other factors to estimate the chance of a heart attack or stroke over ten years. This guides whether to offer lifestyle advice, medicines or both.

NICE guidance on cardiovascular disease risk assessment and lipid modification (NG238) recommends discussing statin treatment for people with a ten-year risk of 10 per cent or more, and for those with established cardiovascular disease, type 1 diabetes in some circumstances, chronic kidney disease and other conditions. The discussion should cover benefits, side effects, preferences and lifestyle. Many people have concerns about statins, and shared decision-making is important.

• Eating more fibre, vegetables, fruit, pulses and wholegrains.

• Replacing saturated fat with unsaturated fat.

• Being physically active on most days.

• Stopping smoking and moderating alcohol.

• Losing weight if overweight.

• Managing blood pressure and diabetes.

Very high LDL cholesterol, especially with a family history of early heart disease, may reflect familial hypercholesterolaemia, a genetic condition. It is under-diagnosed and treatable, and family members can be tested. NHS services offer genetic testing where criteria are met. Symptoms are usually absent, but physical signs such as tendon xanthomas or arcus at a young age may occur.

Private providers offer tests such as apolipoprotein B, lipoprotein(a), small dense LDL and particle numbers. Lipoprotein(a) is largely genetic and may be relevant for people with a family history of early heart disease; it is not routinely measured in primary care. Other advanced tests add information in specific circumstances but may not change management for most people. Ask what decision the test would inform.

Ask which number matters most for your situation, what your estimated ten-year risk is and how it was calculated. Ask what lifestyle changes would make the biggest difference, whether medicine is advised and what the likely benefits and side effects are. If your cholesterol is very high or there is a family history of early heart disease, ask whether familial hypercholesterolaemia should be considered and whether relatives should be tested. Ask when to repeat the test and what to do if you start a statin and develop muscle aches.