What is dyslipidemia?

Dyslipidemia is the presence of an abnormally high level of lipids (fats) or lipoproteins (fat-carrying proteins) in the blood. Lipids are an important part of the body - they are crucial in the formation of cells and as an energy source that our body can break down and use. Sometimes the level of lipids can be abnormally high, which can cause health risks. High levels of lipids and lipoproteins in the blood can build up in the arteries, causing them to harden, become narrow and restrict blood flow, leading to heart attack or stroke.

Arteries

A blood vessel carrying blood saturated with oxygen from the heart to the body's tissues.

Cells

The fundamental unit of life; the simplest living unit that can exist, grow, and reproduce independently. The human body is composed of trillions of cells of many kinds.

Lipids

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.

Lipoproteins

Lipoproteins package cholesterol and other fats with proteins to allow them to move around the bloodstream.

What are lipids?

Lipids, commonly known as fats, consist of cholesterol and triglycerides. Cholesterol is an essential component of all cells. Triglycerides are an important energy source for the body. 

Cholesterol and triglycerides need to be bound to proteins, known as lipoproteins, for them to be transported in the bloodstream to all areas of the body. There are many different lipoproteins with different functions, which collectively help control the level of triglyercides and cholesterol in the blood. The two main lipoproteins that have the greatest influence on the level of cholesterol and triglycerides in the blood are low-density lipoproteins (LDL) and high-density lipoproteins (HDL). LDL help move lipids from the liver to around the body, and often into blood vessel walls. The progressive accumulation of lipids in the vessel walls gives rise to the abnormal hardening and narrowing of blood vessels, known as atherosclerosis. For this reason, LDL is known as 'bad fats'. In contrast, HDL help move lipids to the liver for disposal, hence helping to reduce the risk of artherosclerosis. HDL are known as 'good fats'.   

An excess of cholesterol and triglycerides can pose a risk to a person's health. Numerous factors can lead to high blood lipids, including intake of excess dietary fats, imbalance in lipoprotein levels, cigarette smoking, or certain medications.    

Atherosclerosis

Fatty deposits within arteries of the body.

Cells

The fundamental unit of life; the simplest living unit that can exist, grow, and reproduce independently. The human body is composed of trillions of cells of many kinds.

Cholesterol

A type of fat produced by the body that is necessary for metabolism.

Lipids

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.

Lipoproteins

Lipoproteins package cholesterol and other fats with proteins to allow them to move around the bloodstream.

Triglycerides

A fat or lipid that is composed of one glycerol molecule and three fatty acid molecules. Triglycerides are the most common fat in the blood and levels that are too high can increase the risk of conditions such as diabetes and heart disease.

High-density lipoproteins

Proteins that combine with excess cholesterol to remove it from the blood or artery walls, transport it to the liver and excrete it from the body. High levels of high-density lipoproteins lower the risk of heart disease, whereas low levels increase that risk.

Low-density lipoproteins

Proteins that combine with and transport fats in the blood. About 70% of cholesterol fat is transported by these proteins. High levels of low-density lipoproteins can lead to deposits on walls of arteries, leading to atherosclerosis.

Causes

The causes of dyslipidemia are classed as either primary (genetic), or secondary (lifestyle and other causes).

Primary causes

Primary causes refer to gene mutations that alter the production of lipids or lipoproteins. Genes are comprised of DNA and are the codes within your cells that define what gets made - similar to a recipe. Sometimes, genes can mutate to create more or less of what they are supposed to make. Some people with dyslipidemia have genes that create excess triglycerides, cholesterol or LDL. Alternatively, they could have genes that cause the underproduction of HDL. Individuals with gene mutations tend to have a family history of the condition.  

Secondary causes

Secondary causes of dyslipidemia are related to lifestyle or other medical conditions. A common cause of dyslipidemia is a diet rich in oily or processed foods; in particular, a diet that contains too much saturated fat, cholesterol and trans fats, but is low in unsaturated fats (these are considered healthy fats, which can lower blood cholesterol levels and the risk of heart disease).

Other causes can include:

Beta-blockers

Substances that hinder the activity of hormones such as adrenaline by blocking the beta receptors, found in many organs but particuarly the heart and blood vessels. These are used to treat a range of conditions including high blood pressure and migraines.

Heart disease

A class of diseases that involves the dysfunction of the heart and/or the blood vessels.

Cells

The fundamental unit of life; the simplest living unit that can exist, grow, and reproduce independently. The human body is composed of trillions of cells of many kinds.

Cholesterol

A type of fat produced by the body that is necessary for metabolism.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterised by high blood sugar levels. Also known as diabetes mellitus.

DNA

The genetic material of all living cells and some viruses. The full name is deoxyribonucleic acid.

Gene

A unit of inheritance (heredity) of a living organism. A segment of genetic material, typically DNA, that specifies the structure of a protein or related molecules. Genes are passed on to offspring so that traits are inherited, making you who you are and what you look like.

Genetic

Related to genes, the body's units of inheritance or origin.

Glucocorticoids

A class of drugs that reduce inflammation, commonly used in the treatment of asthma, arthritis and allergic skin conditions. Cortisone is a glucocorticoid.

Lipids

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.

Lipoproteins

Lipoproteins package cholesterol and other fats with proteins to allow them to move around the bloodstream.

Triglycerides

A fat or lipid that is composed of one glycerol molecule and three fatty acid molecules. Triglycerides are the most common fat in the blood and levels that are too high can increase the risk of conditions such as diabetes and heart disease.

HDL

Proteins that combine with excess cholesterol to remove it from the blood or artery walls, transport it to the liver and excrete it from the body. High levels of high-density lipoproteins lower the risk of heart disease, whereas low levels increase that risk.

LDL

Proteins that combine with and transport fats in the blood. About 70% of cholesterol fat is transported by these proteins. High levels of low-density lipoproteins can lead to deposits on walls of arteries, leading to atherosclerosis.

Saturated fat

A type of fat, which chemically does not have double bonds. These fats are usually hard at room temperature and are less healthy than unsaturated fats. Found in foods such as meat with visible fat, full fat-dairy products and plant foods such as palm oil.

Risk factors

Risk factors associated with dyslipidemia include:

  • A family history of dyslipidemia;
  • Smoking;
  • Alcohol abuse;
  • Increased age;
  • Physical inactivity;
  • A diet high in fats, and;
  • Menopause.

Types

Dyslipidemia can be classified into various types, depending on which lipid there is too much of in the blood. The types include:

  • Hypertriglyceridaemia (excess triglycerides in the blood);
  • Hypercholesterolaemia (excess cholesterol in the blood);
  • Hyperlipoproteinaemia (excess lipoprotein in the blood), and;
  • Mixed pattern dyslipidemia, which is a combination of the above types.

Cholesterol

A type of fat produced by the body that is necessary for metabolism.

Lipid

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.

Lipoprotein

Lipoproteins package cholesterol and other fats with proteins to allow them to move around the bloodstream.

Triglycerides

A fat or lipid that is composed of one glycerol molecule and three fatty acid molecules. Triglycerides are the most common fat in the blood and levels that are too high can increase the risk of conditions such as diabetes and heart disease.

Signs and symptoms

In most cases, dyslipidemia does not have any symptoms. It is therefore important to monitor the levels of the different types of lipids in your blood via blood tests. In some cases, dyslipidemia can lead to more serious conditions that do have symptoms, such as heart disease and pancreatitis. Rarely, dyslipidemia can lead to fatty deposits in the iris of the eye (which appears as a white ring around the iris), within tendons (which appear as painless nodules around joints, called xanthoma) and under the skin (which appear as yellow lesions on and around the eyes, called xanthelasma).  

Heart disease

A class of diseases that involves the dysfunction of the heart and/or the blood vessels.

Lesions

Damage to bodily tissue.

Lipids

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.

Nodules

A small growth or lump of tissue.

Pancreatitis

Inflammation of the pancreas.

Tendons

Dense bands of connective tissue that attach muscles to bones.

Methods for diagnosis

Dyslipidemia is diagnosed using a blood test. This identifies the levels of various lipids including triglycerides, total cholesterol, cholesterol bound to LDL (LDL cholesterol) and cholesterol bound to HDL (HDL cholesterol). To get the most accurate result, this is done as a 'fasting test', in which you do not eat for a period of time before your test.

Other tests that your doctor may perform include measuring your levels of glucose, liver enzymes, creatinine, thyroid-stimulating hormone and urinary protein.

Cholesterol

A type of fat produced by the body that is necessary for metabolism.

Creatinine

A chemical waste product of protein metabolism that is filtered from the blood by the kidneys.

Glucose

A simple sugar found in many foods (such as fruit) that functions as a major energy source for the body.

Lipids

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.

Thyroid-stimulating hormone

A hormone produced by the pituitary gland that stimulates the thyroid gland to produce thyroid hormones.

Triglycerides

A fat or lipid that is composed of one glycerol molecule and three fatty acid molecules. Triglycerides are the most common fat in the blood and levels that are too high can increase the risk of conditions such as diabetes and heart disease.

HDL

Proteins that combine with excess cholesterol to remove it from the blood or artery walls, transport it to the liver and excrete it from the body. High levels of high-density lipoproteins lower the risk of heart disease, whereas low levels increase that risk.

LDL

Proteins that combine with and transport fats in the blood. About 70% of cholesterol fat is transported by these proteins. High levels of low-density lipoproteins can lead to deposits on walls of arteries, leading to atherosclerosis.

Liver enzymes

Proteins that help to speed up chemical reactions in the liver. Elevated levels of liver enzymes may be an indication of liver damage or inflammation.

Types of treatment

The aim of treatment is to alter the amount of lipids in your blood to a healthy level. The general recommended goals include reducing triglyceride levels to less than 1.5 mmol/L, total cholesterol to less than 4.0 mmol/L and LDL cholesterol to less than 2.5 mmol/L, and increasing HDL cholesterol to more than 1.0 mmol/L. However, if you have certain underlying medical conditions, such as diabetes, some of these target levels are even lower. 

If your lipid levels are only slightly outside the healthy range, diet and lifestyle changes may be the only treatment required. If your condition is more severe, your doctor can prescribe medications to alter your cholesterol and triglyceride levels.

Diet and lifestyle changes

Diet and lifestyle changes that can help to treat dyslipidemia include:

  • Keeping a healthy body weight;
  • Healthy eating by reducing your intake of foods that have a high fat, cholesterol and salt content; 
  • Eating more fibre, fruit and green vegetables and fish;
  • Reducing your alcohol intake;
  • Quitting smoking;
  • Exercising regularly, and;
  • Drinking more water.

Medications

Depending on the type of lipid disorder, various lipid-lowering medications can be used. Your doctor may prescribe one or more of the following medications:

  • Statins including atorvastatin, pravastatin, simvastatin, fluvastatin and rosuvastatin;
  • Bile acid-binding resins including cholestyramine and colestipol;
  • Fibrates including gemfibrozil and fenofibrate, and;
  • Other agents including ezetimibe, nicotinic acid, probucol and fish oils.

Bile

A fluid made in the liver and stored in the gall bladder.

Cholesterol

A type of fat produced by the body that is necessary for metabolism.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterised by high blood sugar levels. Also known as diabetes mellitus.

Lipids

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.

Statins

A type of medication that lowers cholesterol and can be used to prevent cardiovascular disease.

Triglyceride

A fat or lipid that is composed of one glycerol molecule and three fatty acid molecules. Triglycerides are the most common fat in the blood and levels that are too high can increase the risk of conditions such as diabetes and heart disease.

Fibrates

A group of drugs that lower the level of fats, known as triglycerides, in the blood.

HDL

Proteins that combine with excess cholesterol to remove it from the blood or artery walls, transport it to the liver and excrete it from the body. High levels of high-density lipoproteins lower the risk of heart disease, whereas low levels increase that risk.

LDL

Proteins that combine with and transport fats in the blood. About 70% of cholesterol fat is transported by these proteins. High levels of low-density lipoproteins can lead to deposits on walls of arteries, leading to atherosclerosis.

Potential complications

Potential complications associated with dyslipidemia are related to excess lipids building up in the inner walls of your arteries over time - this is known as atherosclerosis, which causes the arteries to harden and narrow. When this occurs in the arteries that supply blood to the heart, it can cause a condition called coronary artery disease. If an artery becomes completely blocked by a blood clot, it can stop the flow of blood to the heart, preventing the heart tissue from getting enough oxygen. This can cause a heart attack. Coronary artery disease can also cause the heart to weaken over time and contribute to congestive heart failure. Dyslipidemia can also cause peripheral vascular disease, which involves atherosclerosis occurring in other parts of your body. In addition, it can also lead to a stroke.

Atherosclerosis caused by the build-up of lipids in an artery.Atherosclerosis is a complication of dyslipidemia, caused by the build-up of excess lipids in an artery. 

Arteries

A blood vessel carrying blood saturated with oxygen from the heart to the body's tissues.

Atherosclerosis

Fatty deposits within arteries of the body.

Lipids

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.

Clot

The thickened or solid mass formed from a liquid, such as blood. Blood clots normally form at an injury site to prevent further blood loss.

Prognosis

In most cases, dyslipidemia is a treatable condition. For some people, this involves making diet and lifestyle changes, while for others it will also require them to take medication to bring lipid levels into a healthy range. It is important to begin treatment as soon as possible to avoid any long-term complications associated with dyslipidemia.

Lipid

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.

Prevention

In some cases, dyslipidemia can be caused by gene mutations creating high levels of lipids in the blood. Gene mutations cannot be prevented. In many other cases, however, dyslipidemia is caused by diet and lifestyle factors that can be altered to help prevent the condition. These can include maintaining a healthy body weight, reducing fat, avoiding food high in fat and salt, eating more fruit and vegetables and fish, quitting smoking and exercising regularly. It is important to have regular blood tests as part of your general health checks, particularly if you are overweight or have a history of dyslipidemia. This can help to identify any abnormal levels of lipids in your blood and make a treatment plan.

Gene

A unit of inheritance (heredity) of a living organism. A segment of genetic material, typically DNA, that specifies the structure of a protein or related molecules. Genes are passed on to offspring so that traits are inherited, making you who you are and what you look like.

Lipids

A large class of biologically important molecules. Lipids can form fats, vitamins, oils and other substances.