At a glance

Why get tested?

High cholesterol increases the risk of developing heart disease and stroke

When to get tested?
  • If you already know you have heart disease (angina, heart attack)
  • If there is a family history of high cholesterol, or of heart disease at an early age
  • If you are over 45 years old and thereafter every five years or less
  • If you are less than 45 years old and have risk factors which put you at an increased risk of developing heart disease, such as diabetes, high blood pressure, chronic renal failure or renal transplantation, Aboriginal or Torres Strait Islander, overweight or you are a smoker
  • If you are taking drugs to lower your cholesterol level
Sample required?

A blood sample drawn from a vein in the arm or a finger

Test preparation needed?

No fasting is needed for a cholesterol test.
Fasting specimens have traditionally been used for the formal assessment of lipid status. Although European guidelines advise non-fasting specimens, Australia has not yet endorsed it. Therefore if a lipid profile is requested you will need to fast for 9 to 12 hours before the sample is collected. Only water is permitted.
 

What is being tested?

Cholesterol is a substance found almost exclusively in animals. Body fluids including blood and all cells contain some cholesterol which is needed for good health. It forms the membranes for cells and important in production of hormones and bile acids. Cholesterol in blood is in complex particles called lipoproteins. There are different types of lipoproteins. HDL, good cholesterol, removes bad cholesterol from the body, whereas LDL, bad cholesterol, collects in the walls of blood vessels. The test for cholesterol measures all cholesterol (good and bad).

Only a small amount of cholesterol comes from your diet, most is made in your liver. If you have an inherited predisposition for high cholesterol levels or if you eat too much of the foods that are high in cholesterol (e.g. liver, kidney and prawns), saturated fats (e.g. red meat, fried foods, poultry and full-fat dairy products) and trans fats (e.g. deep fried foods and certain baked foods), then levels of cholesterol in your blood may increase and have a negative impact on your health. However cholesterol in food is less important than eating less saturated and trans fats, and more healthy fats (monounsaturated and polyunsaturated fats, omega-3 and omega-6). 

The extra cholesterol in your blood may be deposited in plaques on the walls of blood vessels. Plaques can narrow or eventually block the opening of blood vessels, leading to hardening of the arteries (atherosclerosis) and increasing your risk of numerous health problems, including heart disease and stroke.

How is the sample collected for testing?

Most often a blood sample is collected from a vein in your arm. Sometimes cholesterol is measured using a drop of blood collected by puncturing the skin on a finger.

If lipid levels are abnormal, a second confirmatory sample should be taken on a separate occasion (as levels may vary between tests) before a definitive diagnosis is made.

A finger sample is typically used when cholesterol is being measured on a portable testing device. Screening tests using these capillary blood samples produce total cholesterol results that are slightly lower than on venous blood. A high reading should always be confirmed by testing a blood sample taken from a vein in your arm.

The Test

How is it used?

To screen for risk of developing cardiovascular disease (heart disease, stroke and related diseases) and to monitor treatment.
 

When is it requested?

Cholesterol testing is recommended when you have established heart disease (angina, heart attack), or if there is a family history of high cholesterol, or of heart disease at an early age; if you are less than 45 years of age and have risk factors which put you at an increased chance of developing heart disease, such as diabetes, high blood pressure, chronic renal failure or renal transplantation, Aboriginal or Torres Strait Islander, overweight or you are a smoker. In addition, cholesterol testing is performed if you are following a recommended diet or taking drugs to lower your cholesterol level, to monitor your response to treatment. Total cholesterol may be measured alone or in combination with other tests including HDL, LDL, and triglycerides - often called a lipid profile.

What does the test result mean?

The cholesterol level measured in your blood will be considered along with other risk factors for heart disease (high blood pressure, smoking etc.) when assessing your overall risk of developing heart disease. This overall assessment is what will be used to decide whether or not you require further treatment in the form of lifestyle changes such as diet, exercise or drugs to lower your cholesterol level. 

A total cholesterol level of greater than 7.5 mmol/L is considered high risk. And also this level should be reviewed for family history and clinical features of familial hypercholesterolaemia which is an inherited condition.

If you are taking medication to lower your cholesterol, the target is to get your total cholesterol to a value less than 4.0 mmol/L.

About Reference Intervals

Is there anything else I should know?

Cholesterol testing is recommended as a screening test to be done for all adults with no risk factors for heart disease at least once every four to six years. It is frequently done in conjunction with a routine physical examination. 

Blood cholesterol is temporarily low during acute illness, immediately following a heart attack, or during stress (like surgery or accident). You should wait at least 6 weeks after any illness to have cholesterol measured.

There is some debate about whether very low cholesterol is bad. Low cholesterol is often seen when there is an existing problem like malnutrition, liver disease, or cancer. However there is no evidence that low cholesterol causes any of these problems.

Cholesterol is high during pregnancy. Women should wait at least six weeks after the baby is born to have cholesterol measured.

Some drugs that are known to increase cholesterol levels to a moderate extent, include oral corticosteroids, beta blockers, oral contraceptives, thiazide diuretics, oral retinoids and phenytoin

Familial hypercholesterolaemia (FH) is a severe form of elevated cholesterol levels that runs in families. It is often undetected until damage is done and the person develops cardiovascular disease. It can be easily screened for and treated early in life. Information about FH can be found at the FH Australia network site. Individual risk of having FH can be determined using their online calculator.
 

Common Questions

Who should have a cholesterol screening test?

  • If you already know you have heart disease (angina, heart attack)
  • If there is a family history of high cholesterol or of heart disease at an early age
  • If you are less than 45 years old and have risk factors which put you at an increased chance of developing heart disease, such as diabetes, high blood pressure, chronic renal failure or renal transplantation, Aboriginal or Torres Strait Islander, overweight or you are a smoker
  • If you are taking drugs to lower your cholesterol level
  • If you are over 45 years old.

What causes high cholesterol?

High cholesterol may be the result of an inherited disease or it may result from an unhealthy diet (high in saturated and trans fats, and cholesterol) and lak of exercise. For many people it is caused by a combination of these modifiable factors and an inherited tendency towards high cholesterol.

What treatments are recommended if my levels are too high?

Lifestyle factors should be managed at all risk levels. Healthy diet and other positive lifestyle changes, e.g. increased physical activity, smoking cessation, weight reduction, are quite important. Very high and resistant cholesterol levels need medication. Sometimes two different drugs are used together to treat people with extremely high cholesterol levels. The drug of choice differs for different people. There are several classes of drugs that are commonly used. These include bile acid sequestrants, niacin, HMG-CoA reductase inhibitors (statins) and fibrates. Your doctor will need to take into account your individual situation before prescribing any cholesterol-lowering drug.

What is my risk of a heart attack if I have high cholesterol?

High cholesterol increases your risk of a heart attack. The higher the cholesterol, the higher the risk. However, many other factors also affect your risk of a heart attack, such as gender, smoking, diabetes, age, and high blood pressure. Charts to allow you to assess your risk of a heart attack are available from the National Heart Foundation.

I haven't changed my diet or exercise pattern but my cholesterol has gone up since the last time it was tested. Why?

Cholesterol levels fluctuate over time. The measured cholesterol level may differ by as much as 10% from one month to another. It may go up sometimes or it may go down sometimes. These changes are called biological variation and they represent normal variability inherent in human metabolism.

My doctor told me I had a high cholesterol test but instead of treating me he told me to wait a few months and test it again. Why?

Cholesterol levels fluctuate over time. A single measurement of cholesterol may not always reflect the ‘usual’ cholesterol level. For this reason, it is advisable to have at least two different measurements several weeks to several months apart before beginning any kind of treatment.

Last Review Date: November 7, 2017