

What is this blood test for?

TThe two main groups of lipoproteins are low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Cholesterol is found mainly ...


The doctor is worried about my cholesterol and has sent me to go have a test.

What is a fasting lipid test?


A fasting lipid test is the blood test taken after a sixteen hour fast to measure the level of cholesterol in the blood.

Cholesterol is a fatty substance that plays an important role as part of the outer lining (membrane) of cells in the human body.

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Nearly all of our cholesterol is produced in the liver, and is transported around the body in the bloodstream to the body's cells by special proteins called lipoproteins.

Cholesterol is unable to dissolve in blood without the help of lipoproteins.

The two main groups of lipoproteins are low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Cholesterol is found mainly in foods of animal origin, including dairy products, meat, poultry and fish.

LDL has the job of carrying most of our cholesterol around in the blood. Doctors often refer to LDL cholesterol as 'bad' cholesterol, because a high level of LDL cholesterol is associated with an increased risk of coronary heart disease.

This can happen because LDL causes cholesterol to accumulate and harden on the artery walls, leading eventually to thickening of the artery walls and narrowing of the arteries, the process of atherosclerosis.

If our coronary arteries that supply blood and oxygen to the heart muscles are affected they can become incapable of supplying enough blood and oxygen to the heart muscle under certain conditions, eg during exercise.

Lack of oxygen (ischaemia) to the heart muscle causes muscle cramp and chest pain (angina).

In the worst-case scenario, formation of a blood clot in the coronary artery can cause a complete blockage of the artery, leading to death of heart muscle (heart attack).

HDL on the other hand is extremely helpful to us by actually removing cholesterol from our artery walls, and protecting us from atherosclerosis.

Doctors refer to HDL cholesterol as 'good' cholesterol, high levels being desirable, while low HDL cholesterol increases our risk of coronary heart disease.

Remember, cholesterol is but ONE risk factor for heart disease. What is a 'safe level' for you is dependent on other personal factors, such as your smoking history, blood pressure, weight, whether or not you have diabetes, any family history of early coronary heart disease and your age.

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You could discuss whether or not to have such a test with your doctor. If you discover that you are at an increased risk, they will be able to explain how you can best help yourself for the rest of your life.

Yours sincerely

The NetDoctor Medical Team

Last updated

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