High Cholesterol (hypercholesterolemia)

What is hypercholesterolemia?

Hypercholesterolemia (also called dyslipidemia) is the presence of high levels of cholesterol in the blood. Cholesterol is a type of fat (lipid) that is part of all animal cells. It is essential for many of the body’s metabolic processes including the production of hormones, bile and vitamin D. Cholesterol is produced by the liver and the body is very good at making enough for its own requirements without supplementing through dietary intake. There are two main types of cholesterol, HDL is the ‘good’ cholesterol and LDL is the ‘bad’ cholesterol. If you have too much ‘bad’ cholesterol, it starts to build up in your arteries causing hardening of the arteries or atherosclerosis. It is usually a slow process that gets worse as you get older but can lead to serious problems, including heart attack and stroke.

Elevated levels of LDL cholesterol in the blood may be a consequence of diet, obesity, inherited (genetic) diseases, or the presence of other diseases such as diabetes and underactive thyroid. Lifestyle changes such as more exercise and reducing saturated dietary fat is recommended to reduce total blood cholesterol and LDL in adults. However, in people with genetic/family history causes, diet is often insufficient to achieve the desired lowering of LDL and medications which reduce cholesterol production or absorption are usually required.

Approximately half of all adult Australians have a blood cholesterol level above the recommended target level. This makes high blood cholesterol a major health concern in Australia.

How is high cholesterol diagnosed?

Cholesterol can’t move around in the bloodstream on its own and is transported in the blood by little ‘couriers’ called lipoproteins. There are two major types of lipoproteins, namely high-density lipoprotein (HDL) and low-density lipoprotein (LDL). High levels of HDL are considered good for you, whereas high levels of LDL aren’t so good and can result in future health problems.

Low-density lipoprotein (LDL) cholesterol – carries most of the cholesterol that is delivered to cells. It is called the ‘bad’ cholesterol because when its level in the bloodstream is high, it can clog up your arteries.

High-density lipoprotein (HDL) cholesterol – is called the ‘good’ cholesterol, because it helps remove excess cholesterol out of the cells and takes it back to the liver where it can be broken down and excreted.

Health authorities recommend that total cholesterol levels should be no higher than 5.5 mmol per litre if there are no other risk factors present. If there are other cardiovascular risk factors such as smoking and high blood pressure or pre-existing/hereditary cardiovascular (heart) disease, then the aim for total cholesterol is to be below 4 mmol/L and for the LDL levels to be less than 2 mmol/L.

You will need a doctor to perform a blood test to check your levels as high cholesterol doesn’t usually make you feel sick and rarely presents with any symptoms.

What causes high cholesterol?

Hypercholesterolemia is typically due to a combination of environmental and genetic factors. Environmental or lifestyle issues are the major cause of high cholesterol, most of which are treatable and even preventable. Lifestyle factors such as eating foods containing high levels of saturated fats, being overweight or obese and not exercising all cause an increase in LDL levels. Existing conditions such as high blood pressure, diabetes, kidney or liver disease or an underactive thyroid gland can also result in raised cholesterol. Treating these conditions can often be helpful in reducing LDL levels.

For some people, diet and lifestyle changes are not enough as high blood cholesterol levels can often have a genetic component. Some people inherit altered genes that cause higher than normal cholesterol production by the liver and this cannot usually be changed sufficiently by lifestyle or diet. Blood cholesterol levels also increase with age.

What happens if high cholesterol is untreated?

Having high cholesterol can lead to the buildup of plaque in artery walls. This buildup is called atherosclerosis. It can lead to coronary artery disease (CAD), heart attack, stroke or transient ischemic attack (TIA), and peripheral arterial disease. Atherosclerosis can cause these problems because it:

  • Narrows your arteries. When enough plaque builds up, it starts to narrow your arteries. This happens slowly over many years. In time, the plaque can limit blood flow throughout your body, including the heart and brain.
  • Hardens your arteries. A healthy artery can widen (dilate) so that more blood can flow through when needed, such as during activity. When hard plaque forms in the walls of an artery, it can make the artery too stiff to widen. This “hardening” of your arteries can also limit blood flow in your body.
  • Blocks your arteries. When a blood clot forms around a crack or rupture in the plaque, it can block the artery. This can cause a heart attack or stroke.

Treatment methods for high cholesterol

The most important thing you can do to reduce your cholesterol level is to maintain a healthy lifestyle. Changing some of your lifestyle habits can help to reduce your bad cholesterol and increase your good cholesterol levels. You should try to:

  • Increase the amount and variety of fresh fruit, vegetables and wholegrain foods you have each day.
  • Avoid processed and fatty meats, snack foods like chips, cakes, biscuits, pastries and deep fried foods.
  • Choose low or reduced-fat milk, yoghurt and other dairy products.
  • Include foods in your diet that are rich in soluble fibre and healthy fats, such as nuts, legumes and seeds.
  • Cease alcohol consumption or reduce your alcohol intake to no more than one or two drinks a day. Avoid binge drinking. This may help lower your triglyceride levels.
  • Don’t smoke. Smoking increases the ability of LDL cholesterol to get into artery cells and cause damage.
  • Exercise regularly (for example, at least 30 minutes of brisk walking daily). Exercise increases HDL levels while reducing LDL and triglyceride levels in the body.
  • Lose any excess body fat. Being overweight may contribute to raised blood triglyceride and LDL levels.
  • Control your blood sugar levels if you have diabetes. High blood sugars are linked to an increased risk of atherosclerosis (‘hardening of the arteries’), heart attacks and strokes.

If you are at risk of coronary heart disease and your LDL cholesterol level doesn’t drop after scrupulous attention to diet, your doctor may recommend medications to force your blood LDL levels down. Statins (or HMG-CoA reductase inhibitors) are commonly used to treat hypercholesterolemia if diet is ineffective. Other medications that may be used include: fibrates, nicotinic acid, and cholestyramine. However, these are usually only recommended if statins are not tolerated or in pregnant women.  You should speak to your doctor to discuss your cholesterol levels and any treatment required.

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