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High cholesterol: Overview

Created: ; Last Update: September 7, 2017; Next update: 2020.

Introduction

Many people worry about their cholesterol because high cholesterol levels in the blood can increase the risk of cardiovascular disease.

People are considered to have high cholesterol (“hypercholesterolemia”) when certain levels are exceeded. High cholesterol levels are not a medical condition on their own. Also, there are different opinions on what is considered to be too high. It is important to remember that high cholesterol is just one of many risk factors for cardiovascular disease. This means that cholesterol levels alone tell us little about a person’s risk.

Symptoms

High cholesterol doesn't in itself cause any symptoms. But if someone has high cholesterol over many years, their risk of cardiovascular disease – such as angina, heart attacks and strokes – might be higher than normal for their age. So it can be a good idea for people who have high cholesterol to do something about it.

Causes

Cholesterol levels mainly depend on your genes and lifestyle.

Some people already have very high cholesterol as children because of their genes. This is known as familial or primary hypercholesterolemia. There are various types of this kind of problem, which sometimes poses a serious health risk.

But in most people, cholesterol levels are mainly influenced by lifestyle factors such as diet and exercise habits. This is called acquired hypercholesterolemia.

Sometimes people’s cholesterol levels increase because of a medical condition they have, such as an underactive thyroid gland. Taking certain medications can also make your cholesterol levels go up somewhat.

Risk factors

As a general rule, the higher the cholesterol levels, the higher the risk of cardiovascular disease. But cholesterol isn't the only risk factor. Many other things can have an influence – both positive and negative. The risk of cardiovascular disease can only be properly assessed if all the factors are considered together.

People’s individual risk can be determined with the help of special tables or computer programs, sometimes called risk calculators. This is best done together with a doctor. Various pieces of information about risk factors are needed in order to calculate the risk. These are the main risk factors:

  • Age: The risk of cardiovascular disease increases with age.
  • Sex: Men are at higher risk than women.
  • Family history: People are at greater risk if they have a brother or father who had a heart attack or stroke before the age of 55, or if they have a sister or mother who had a heart attack or stroke before the age of 65.
  • Smoking: Smoking increases the risk more than, for instance, moderately high cholesterol levels.
  • High blood pressure: High blood pressure (hypertension) puts extra strain on the heart and blood vessels.
  • Type 2 diabetes: People who have type 2 diabetes have a greater risk of cardiovascular disease than people of their age who don't have diabetes.
  • Cholesterol levels: High total cholesterol, high LDL cholesterol (“bad” cholesterol) and low HDL cholesterol (“good” cholesterol) are potentially harmful.

When someone's risk of cardiovascular disease is estimated, it is generally described in terms of the likelihood of having a stroke or heart attack within the next ten years. The following tables show examples with two women (Veronica and Isabel) and two men (Fred and Carl) to demonstrate how important it is to consider all of the risk factors together.

Table: Influence of different risk factors in women

Risk factorVeronicaIsabel
Total cholesterolHigh(260 mg/dL)High (260 mg/dL)
HDL cholesterolSlightly low (44 mg/dL)Slightly low (44 mg/dL)
Age50 years old50 years old
Genetic predispositionNone Father: Heart attack before the age of 55
SmokesNoYes
Blood pressureSlightly high(145/90 mmHg) Slightly high (145/90 mmHg)
Type 2 diabetesNoNo
Risk of a heart attack or stroke within the next ten years4%18% 

Table: Influence of different risk factors in men

Risk factorFredCarl
Total cholesterolHigh (260 mg/dL)High (260 mg/dL)
HDL cholesterolSlightly low (44 mg/dL)Slightly low (44 mg/dL)
Age50 years old50 years old
Genetic predispositionNoNo
SmokesNoYes
Blood pressureNormalVery high (162/96 mmHg)
Type 2 diabetesNoNo
Risk of heart attack or stroke within the next ten years11%33%

Source: www.arriba-hausarzt.de

Although all of the above four people have the same cholesterol levels, their individual risk of cardiovascular disease is very different. So cholesterol levels alone don't tell us much. They are therefore usually not a suitable basis for deciding whether or not to have cholesterol-lowering treatment.

By the way, the risk of a 50-year-old having a heart attack or stroke in the next ten years if they don't have any risk factors is 3% for men, and under 1% for women.

Diagnosis

Cholesterol doesn't dissolve in water (or blood). To be able to transport it in the blood, our bodies pack cholesterol into tiny parcels, together with various proteins and other things in our blood. Depending on what else is packed into those parcels, they make up different kinds of cholesterol that can be distinguished between in a laboratory.

When looking at cholesterol levels, two different types are usually measured. The two types have different effects on cardiovascular health. In everyday language they are often referred to as “good” and “bad” cholesterol:

  • HDL cholesterol: HDL (high-density lipoprotein) cholesterol levels are a measure of the proportion of “good” cholesterol in your total cholesterol. Normal to high HDL cholesterol levels are associated with a lower risk of cardiovascular disease than low HDL cholesterol levels.
  • LDL cholesterol: LDL (low-density lipoprotein) cholesterol levels are a measure of the proportion of “bad” cholesterol. High LDL cholesterol levels are associated with a higher risk of cardiovascular disease.

The “total cholesterol” level is also measured. This describes how much cholesterol someone has in their blood overall. High total cholesterol levels tend to be unfavorable. It is best to measure total cholesterol and LDL cholesterol levels on an empty stomach. That is why people are asked to stop eating, and only drink water, twelve hours before being tested.

There is some disagreement about when cholesterol levels are “too high.” People are often diagnosed with hypercholesterolemia if their total cholesterol or LDL cholesterol is above the level that has been defined as “healthy.” HDL cholesterol levels below the threshold level are also considered to be unfavorable. These levels can be measured in two different units: either as milligrams per deciliter (mg/dL) or as millimoles per liter (mmol/L). The following levels are considered to be "good" in healthy people:

  • Total cholesterol: Levels below 200 mg/dL (5.2 mmol/L)
  • LDL cholesterol: Levels below 130 mg/dL (3.4 mmol/L)
  • HDL cholesterol: Levels above 40 mg/dL (1 mmol/L) in men and above 50 mg/dL (1.3 mmol/L) in women

Some experts criticize the use of pre-defined threshold levels because it means that a large number of people are considered to have a health problem. Based on these definitions, a 2010 study by the Robert Koch Institute found that more than half of all Germans had high cholesterol.

Screening

In Germany, people covered by statutory health insurance are entitled to a general health check-up every two years from the age of 35. The aim of this check-up is to detect early signs of cardiovascular disease, diabetes and kidney problems. It involves things like having your blood pressure taken, and blood and urine tests. Total cholesterol is measured too.

Treatment

Treatment for high cholesterol is not only about lowering cholesterol levels. Instead, it is more about reducing a higher risk of cardiovascular disease to a normal level, if possible. Treatments can only be considered well tested if researchers have also looked at whether they actually prevent heart disease.

People who are at higher risk of cardiovascular disease are often advised to follow some general measures as part of their treatment. These include the following:

  • Not smoking
  • Reducing the amount of saturated fats in your diet
  • Eating a “Mediterranean diet”
  • Getting a lot of exercise
  • Losing weight

Some of these measures may also lower cholesterol levels.

As with other kinds of treatment, when assessing medications it isn't enough to look only at how they affect cholesterol levels. So far only one group of medications, known as statins, has been studied for the treatment of high cholesterol in people who, however, haven't had a heart attack, stroke or other cardiovascular disease. Statins have been shown to lower LDL cholesterol levels, and also seem to have other positive effects on blood vessels. There is some disagreement among researchers about whether the beneficial effects of statins are only due to their cholesterol-lowering ability or whether other factors play a role too.

Sources

  • Absolutes und relatives Risiko – individuelle Beratung in der Allgemeinpraxis (Arriba). Arriba Herz Risikokalkulationsbogen. August 2013.
  • American Heart Association (AHA). What Your Cholesterol Levels Mean. July 05, 2017.
  • Scheidt-Nave C, Du Y, Knopf H, Schienkiewitz A, Ziese T, Nowossadeck E et al. Verbreitung von Fettstoffwechselstörungen bei Erwachsenen in Deutschland. Ergebnisse der Studie zur Gesundheit Erwachsener in Deutschland (DEGS1). Bundesgesundheitsbl 2013; 5/6: 661-667. [PubMed: 23703484]
  • IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

    Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.

    Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

© IQWiG (Institute for Quality and Efficiency in Health Care)
Bookshelf ID: NBK279318

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