High cholesterol level (hypercholesterolaemia)

However, it is now recognised that the significance of any particular cholesterol level cannot be assessed without taking into account the ratio between good and bad cholesterol (either total-cholesterol/HDL-cholesterol ratio or LDL-cholesterol/HDL cholesterol ratio) or the presence of other cardiovascular risks, such as smoking, diabetes and high blood pressure (hypertension).

It is possible for someone to have a high level of total cholesterol and still have a relatively low cardiovascular risk because of an absence of other risk factors or because their family history is free from coronary disease.

Anyone with an established track record of cardiovascular disease such as angina pectoris, a previous heart attack, coronary angioplasty or coronary bypass surgery should seek advice to keep their total cholesterol level below 5mmol/l or their LDL below 3mmol/l.

What cause high cholesterol levels?

. Cholesterol levels can run in families. If the inherited cholesterol levels are very high, this is called familial hypercholesterolaemia or familial combined hyperlipidaemia (FCH) where the triglyceride levels are very high as well.

Levels can also be influenced by the part of the world you live in: cholesterol levels in northern European countries are higher than in southern Europe and much higher than in Asia.

It is known that the relationship to food is significant, but there is no doubt that genes also play a part. High cholesterol is also seen in connection with other diseases, such as reduced metabolism (due to thyroid hormone problems, for example), kidney diseases, diabetes and alcohol abuse.

What are the symptoms of high cholesterol in the bloodstream?

You cannot tell if you have a high cholesterol level, but a high level in conjunction with other adverse factors increases the risk of developing atherosclerosis and cardiovascular disease.

Atherosclerosis results in narrowing of the arteries. This does not occur suddenly, but builds up over many years during which cholesterol and fat have been deposited in the artery walls. The result is that the arteries become constricted and hardened, their elasticity disappears and the volume of blood able to travel through them is reduced.

The symptoms are therefore the consequences of cardiovascular disease. They depend on the degree of narrowing, the likelihood that the plaque is going to rupture (vulnerability), and the organ supplied by the affected arteries.

- In the brain, an atherosclerotic carotid or cerebral (brain) artery might block with clotted blood (thrombus) or a smaller intracerebral vessel may rupture causing a local haemorrhage. Both these circumstances result in a stroke (cerebrovascular accident or CVA).
- In the heart, narrowed coronary arteries cause angina, and ruptured plaques cause coronary thrombosis (myocardial infarct or heart attack), which may lead to reduced heart function (heart failure) if a significant amount of heart muscle is damaged.

What can be done to prevent vascular disease?

. High cholesterol is only one of many risk factors in the development of hardening of the arteries. These factors include:

- smoking: recent research shows that middle-aged women and men who smoke have a much higher risk of suffering a heart attack. The risk drops in the years following giving up smoking.
- diet: food is another important factor. A Mediterranean diet made up of bread, fruits, vegetables and small amounts of lean meat, fish, and olive oil is recommended.
- alcohol: moderate consumption reduces the negative effect of the LDL-cholesterol and increases HDL-cholesterol. Too much raises blood pressure and damages the liver, having an adverse overall effect.
- exercise: even on a small scale this can reduce the chance of coronary artery disease. Hard physical exercise increases the blood's ability to break up blood clots.
- body weight: it is important to avoid obesity, especially when the fat is around the stomach.

How does the doctor make the diagnosis?

After a 12-hour fast, during which only water can be consumed, a blood sample is taken to measure the level of cholesterol, LDL-cholesterol, HDL-cholesterol and triglyceride in the blood. The cholesterol count rises during pregnancy and drops significantly in connection with a heart attack and other serious illnesses.

The doctor can seek evidence of cardiovascular disease by checking the pulse, the blood pressure, listening to the heart and large arteries, checking kidney function with a blood test and arranging an electrocardiogram .

In some patients with inherited or familial high cholesterol, it is possible to see deposits of cholesterol in the skin, eyes and tendons.

How is raised cholesterol in the blood treated?

Medical treatment with cholesterol-lowering medicine is needed when there is established heart or arterial disease (cardiovascular disease) and the total cholesterol remains greater than 5mmol/l.

Cardiovascular risk may be calculated from a patient's risk factor profile and family history. In the UK it has been recommended that medical therapy should be initiated where the individual's risk of coronary disease is greater than 30 per cent over 10 years.

The most effective medications for lowering cholesterol are the statins. Although these are normally very effective, non-statin treatments such as Ezetrol are available if there are any problems with statin side effects such as muscle pains.

There are now very useful national guidelines to help your doctor estimate the 'cardiovascular risk' associated with your cholesterol levels and blood pressure readings.

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