Summary

• The lipid profile is a group of blood tests that measures different types of cholesterol including LDL or low-density lipoprotein cholesterol, and HDL or high-density lipoprotein cholesterol, together with another form of fat, called triglycerides.
• This can help find out if you are at risk of developing atherosclerosis – a buildup of plaque in your arteries and blood vessels that can lead to heart disease and stroke (known as cardiovascular disease or CVD).
• When assessing your CVD risk, your lipid levels will be considered along with other factors such as high blood pressure, obesity, diabetes and smoking.
• Lipids can be measured after you have fasted or even if you have not fasted. This is called a random lipids test. The type of test will be selected depending on what your medical team is seeking to achieve.  

What are lipids?

Lipid profile tests are used to predict your risk of developing cardiovascular diseases (CVD) such as heart disease and stroke in the next 5 or 10 years.

The tests measure different types of cholesterol together with triglycerides in a sample of your blood. Cholesterol and triglycerides are lipids, or fats.

Cholesterol

Cholesterol is a waxy, fat-like substance found in every cell of your body and is involved in a whole host of vital processes such as building cells and making hormones. About 80 per cent of the cholesterol you need is made in your liver, and the rest comes from foods you eat.

Triglycerides

Triglycerides are the most common type of fat in the body and the main source of energy. When you eat, your body converts any calories it doesn't need into triglycerides. Later, your body releases triglycerides for energy between meals. Most triglycerides are found in body fat, and some circulate in the blood. Higher amounts of triglycerides will be found in your blood after eating a meal, when fat is being sent from the gut to body fat for storage. Having the right levels of triglycerides is important for overall heart health.

What are lipoproteins?

Cholesterol and triglycerides are fats and therefore cannot be dissolved in water. As your blood is a liquid, they need help to move through it. They are processed in the liver where they are packaged up with proteins into round particles called lipoproteins. This enables them to move through blood rather than rising to the top, like oil on water. In this way, they travel to organs and tissues where and when they are needed for energy or storage.      

There are different types of lipoproteins depending on the amounts of fat and protein they contain. They are termed high-density lipoprotein (HDL) and low-density lipoprotein (LDL). There are also different subtypes of lipoproteins such as very low-density lipoprotein (VLDL) and intermediate density lipoprotein (IDL). In general, lipoproteins with a higher fat content and lower protein content (e.g. lower density such as LDL and VLDL) are more likely to stick to artery walls and cause a buildup of plaques. 

How lipids form plaques in artery walls

Although lipids are essential for many of your body’s functions, having too much LDL in your blood is harmful. Your body has systems in place for getting rid of excess lipids but sometimes these systems don’t work as they should, or they become overloaded.  Some people inherit genetic conditions that cause them to have too much LDL regardless of their diet or lifestyle.

When you have high amounts of cholesterol and triglycerides circulating in your blood packaged up in low-density lipoprotein, they stick together with other fats, cells, calcium and debris floating around in the bloodstream and form plaques in the walls of arteries. The buildup of plaque narrows the space within the artery.  

Over time, a tough, fibrous cap or scar forms over the soft sticky plaque. This is a defence mechanism by your body to stabilise the plaque and stop it breaking open. If the cap is thin or becomes inflamed and breaks open – such as if your blood pressure spikes – a blood clot forms over the rupture. This blocks the blood flow which has the potential to lead to a heart attack or stroke.

There are different types of plaques. Some grow slowly and may never cause problems even when the plaque is large enough to restrict blood flow through the artery while others are unstable. These plaques with thin and weak caps are more likely to burst. Most heart attacks occur when small plaques break open or rupture. Plaque buildup – atherosclerosis – can lead to serious problems like:

• Coronary artery disease – blocked blood flow to your heart.
• Peripheral artery disease –blocked blood flow to your legs and arms.
• Carotid artery disease – blocked blood flow to your brain.

Why get tested?

You may be asked to have a lipid profile test if you:

• are over 45 years,
• are less than age 45 but have risk factors that put you at an increased chance of developing heart disease, such as diabetes, high blood pressure, chronic kidney failure or have received a kidney transplant, being of Aboriginal or Torres Strait Islander heritage, overweight or a smoker, or already have heart disease (angina, heart attack),
• have a family history of high cholesterol or of heart disease at an early age, or
• are taking drugs to lower your cholesterol level.

The lipid profile

The lipid profile measures different types of cholesterol and triglycerides in a blood sample:

• Low-Density Lipoprotein (LDL) or ‘bad’ cholesterol is made mostly of cholesterol and has less protein than HDL. This means they can deposit cholesterol into blood vessel walls causing plaques to form. By lowering LDL it’s possible to reduce the cholesterol inside plaques. LDL blood levels are calculated using a formula using total cholesterol, HDL and triglyceride levels.
• High-Density Lipoprotein (HDL) or ‘good’ cholesterol is made up of more protein and has less cholesterol than LDL. It helps remove cholesterol from artery walls. Having a normal HDL level is important. HDL levels are measured along with total cholesterol and triglycerides.
• Total cholesterol is the measurement of all the cholesterol carried by lipoproteins in your blood sample.  
• Non-HDL cholesterol is a measurement of all the cholesterol other than HDL. It is your HDL or good cholesterol number subtracted from your total cholesterol number – a measure of all the bad types of cholesterol.
• Cholesterol/HDL ratio is reached by dividing your total cholesterol measurement by your HDL measurement. A higher ratio means you have a higher risk. It is thought to be a better predictor of heart disease and stroke risk.  
• Triglycerides is fat from the food we eat. High amounts of triglycerides in your blood can contribute to the formation of plaques in the arteries. They increase your risk of heart disease and stroke as well as your risk of pancreatitis.

Sometimes, further lipids tests will be performed:

• Very low-density lipoprotein (VLDL) cholesterol: VLDLs carry triglycerides and cholesterol, and their protein content is low. They are ‘bad’ because they help form plaques  in your arteries. VLDL levels are not measured directly but rather estimated from the level of triglycerides.
• Lipoprotein(a): Lipoprotein(a) or Lp(a) is another type of bad lipoprotein. In Lp(a), the LDL particles are stickier. High Lp(a) levels are inherited – a person’s Lp(a) level is mostly due to their genes and the level does not change much as they age. Your medical team may request an Lp(a) test to decide on your risk of arterial disease if you have a strong family history of heart attack at a relatively young age.
• Apolipoprotein- A-1: A low level of Apo A-1 in the blood is associated with a low level of HDL, the ‘good’ cholesterol in the blood. This suggests your body is not getting rid of excess cholesterol well enough and may increase your chance of arterial disease.
• Apolipoprotein- B-100: Apo B-100 is a protein that is part of very low-density and low-density lipoproteins. Each low-density and very low-density lipoprotein contains exactly one Apo B-100 particle, making measuring Apo B-100 a useful way to assess the amount of non-HDL in your blood.

Inherited high cholesterol levels - Familial Hypercholesterolaemia (FH)

About 1 in 250 people have a genetic change that increases their risk of having high LDL-cholesterol which puts them at a greater risk of heart disease earlier in life. This is called Familial Hypercholesterolaemia (FH). Genetic testing for FH is available. 

Having the test

Sample

Blood.

Any preparation?

Fasting lipid testing and random lipid testing are two approaches to measuring lipid levels in your blood:

• Fasting Lipid Testing: You need to fast for 8-12 hours before the test, meaning you should not eat or drink anything except water. Fasting means that recent food intake does not affect your test results, providing a more accurate measurement of your lipid levels.
• Random Lipid Testing: This test does not require fasting, so you can eat and drink normally before the test. More recent studies show that random (non-fasting) lipid testing can provide accurate results, and it is more convenient and safer for people with diabetes as they do not have to fast.

Fasting samples are still preferred in certain cases such as if you have a high triglyceride level, a metabolic condition such as familial hypercholesteraemia or metabolic syndrome. Metabolic syndrome is a cluster of conditions that occur together that increase your risk of heart disease, stroke, and type 2 diabetes. These conditions include increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels. Your medical team will let you know if a fasting or random sample is required for your lipid test. 

Your results

Reading your test report
Your results will be presented along with those of your other tests on the same form. You will see separate columns or lines for each of these tests. If your results are higher than they should be, a second blood sample should be taken on a separate occasion before a definitive diagnosis is made, as levels may vary between tests.  You should discuss the results of your lipid profile test with your doctor. There are specific guidelines for target cholesterol levels in different people.

Repeat testing

Your cholesterol level may differ by as much as 10 per cent from one month to another. Tests repeated over several months will give a good picture of the true state of your cholesterol.

The Australian CVD risk calculator

Your doctor will use your results to estimate your overall risk of cardiovascular disease (CVD). Cardiovascular refers to the heart and blood vessels.

This risk calculation includes other CVD risk factors such as high blood pressure, age, diabetes, and smoking. Your risk score can be calculated using the Australian CVD risk calculator.

Assessing your CVD risk depends on your age. Age ranges for assessing CVD risk is recommended for:

• People without known CVD, from age 45 to 79. 
• People with diabetes without known CVD, from age 35 to 79.

For First Nations people without known CVD:

• Assess individual CVD risk factors from age 18 to 29.
• Assess CVD risk using the Australian cardiovascular disease risk calculator from age 30 to 79.

When are you likely to be advised to have treatment?

Your target cholesterol levels will depend on your personal situation and your level of risk.

The following groups are recommended for treatment by the Royal Australian College of General Practitioners, although treatment may be recommended even if you do not fit into any of these categories. If you have:

• an absolute CVD risk of more than 15 per cent,
• pre-existing cardiovascular disease,
• diabetes and are aged over 60, or if you have diabetes-related kidney disease,
• chronic kidney disease,
• moderate or severe high blood pressure (hypertension),
• a total cholesterol level of more than 7.5 mmol/L,
• are of Aboriginal or Torres Strait Islander background and aged over 74, or 
• have the genetic condition, Familial Hypercholesterolaemia (FH).

Any more to know?

A more comprehensive lipid profile that includes lipid particle size can be performed. However, this type of testing is expensive and not eligible for a Medicare rebate.

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods, medications or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How could it change the course of my care?
• What will happen next, after the test?

More information

Pathology and diagnostic imaging reports can be added to your My Health Record.

You and your healthcare provider can now access your results whenever and wherever needed. Get further trustworthy health information and advice from healthdirect.