Cholesterol, high - Diagnosing high cholesterol - getting a cholesterol test

Blood cholesterol levels are measured with a simple blood test. This blood sample will be used to determine the amount of LDL (bad cholesterol), HDL (good cholesterol) and triglycerides (other fatty substances) in your blood.

You may be asked not to eat for 10-12 hours before the cholesterol test (usually including when you are asleep at night). This ensures that all food is completely digested and will not affect the outcome of the test.

Your GP or practice nurse can carry out the cholesterol test and will take a blood sample either using a needle and a syringe or by pricking your finger.

Results

At the end of your assessment your healthcare professional will explain your results and will calculate whether you have a high, moderate or low risk of getting cardiovascular disease (heart disease or stroke) within the next 10 years.

However, this risk is not just based on your cholesterol reading – it also takes into account:

your BMI (body mass index), which measures your weight in relation to your height
treatable risk factors, such as high blood pressure (hypertension), diabetes and other medical conditions
your age, sex, family history and ethnicity

The ideal cholesterol levels for healthy adults and for those at high risk of cardiovascular disease are explained below.

Total cholesterol level

Blood cholesterol is measured in units called millimoles per litre of blood, often shortened to mmol/L.

The government recommends that total cholesterol levels should be:

5mmol/L or less for healthy adults
4mmol/L or less for those at high risk

In the UK in 2011, around 50% of adults had a cholesterol level above 5mmol/L. This figure has been improving steadily since the last measurement in 2003.

On average, men in England have a cholesterol level of 5mmol/L and women have a level of 5.1mmol/L.

Levels of LDL and HDL

The government recommends that levels of low-density lipoprotein (LDL) should be:

3mmol/L or less for healthy adults
2mmol/L or less for those at high risk

An ideal level of high-density lipoprotein (HDL) is above 1mmol/L. A lower level of HDL can increase your risk of heart disease.

Your ratio of total cholesterol to HDL may also be calculated. This is your total cholesterol level divided by your HDL level. Generally, this ratio should be below four, as a higher ratio increases your risk of heart disease.

Triglycerides

Your doctor or nurse may also measure your level of triglycerides. Triglycerides are the fats you use for energy and come from the fatty foods you eat. You store what you do not use in the fatty tissues of your body. Excess triglycerides in the blood also increase heart problems.

Your ideal level of triglycerides should be less than 1.7mmol/l.

Who should be tested?

Your GP may recommend that you have your blood cholesterol levels tested if you:

have been diagnosed with coronary heart disease, stroke or mini-stroke (TIA) or peripheral arterial disease (PAD)
are over 40years old
have a family history of early cardiovascular disease (for example, if your father or brother developed heart disease or had a heart attack or stroke before the age of 55, or if your mother or sister had these conditions before the age of 65)
have a close family member who has a cholesterol-related condition, such as familial hypercholesterolaemia (inherited high cholesterol)
are overweight or obese
have high blood pressure or diabetes
have another medical condition such as a kidney condition, an underactive thyroid gland or an inflamed pancreas (pancreatitis). These conditions can cause increased levels of cholesterol or triglycerides