Patient information: High cholesterol and lipids (hyperlipidemia)

INTRODUCTION

Hyperlipidemia refers to increased levels of lipids (fats) in the blood, including cholesterol and triglycerides. Although hyperlipidemia does not cause a person to feel bad, it can significantly increase the risk of coronary heart disease (CHD). People with CHD develop thickened or hardened arteries in the heart muscle. This can cause chest pain, a heart attack, or both. Because of these risks, treatment is often recommended for people with hyperlipidemia.

This topic reviews the risk factors for coronary heart disease, the types of lipids, and when cholesterol testing should begin. The treatment of high cholesterol is discussed separately. (See "Patient information: High cholesterol treatment options".)

OTHER RISK FACTORS FOR CORONARY HEART DISEASE

In addition to hyperlipidemia, there are a number of other factors that increase the risk of CHD and its complications.

The following are CHD-risk equivalents; people with these underlying medical problems are thought to be at the same risk for complications of heart disease as people with known CHD.

• Diabetes mellitus, type 1 and 2 (see "Patient information: Diabetes mellitus type 1: Overview" and "Patient information: Diabetes mellitus type 2: Overview".
• Symptomatic carotid artery disease (eg, stroke or transient cerebral ischemia) (see "Patient information: Transient ischemic attack" and "Patient information: Stroke symptoms and diagnosis".
• Peripheral arterial disease (eg, claudication) (see "Patient information: Claudication (peripheral arterial disease)".
• Abdominal aortic aneurysm (see "Patient information: Abdominal aortic aneurysm".

Other characteristics that increase the risk of coronary heart disease include the following:

• Cigarette smoking
• Hypertension (blood pressure ≥140/90 or use of blood pressure medication) (see "Patient information: High blood pressure in adults".
• Family history of premature CHD in a first degree relative (includes parents and siblings). In males: first degree relatives <55 years, in females: first degree relative <65 years
• Gender: Men have a higher risk of CHD than women at every age
• Age: There is an increasing risk of CHD with increasing age

LIPID TYPES

There are many different types of lipid particles (lipoproteins). Blood tests can determine levels of the most commonly measured lipoproteins. The standard lipid blood tests include a measurement of total cholesterol, LDL and HDL cholesterol, and triglycerides.

Total cholesterol — An elevated total cholesterol level is associated with an increased risk of CHD (graph 1). A desirable total cholesterol level is usually less than 200 mg/dL (5.17 mmol/L). A total cholesterol level of 200 to 239 mg/dL (5.17 to 6.18 mmol/L) is borderline high, while a value greater than or equal to 240 mg/dL (6.21 mmol/L) is high. However, most decisions about treatment are made based upon the level of LDL or HDL cholesterol, rather than the level of total cholesterol.

The total cholesterol can be measured any time of day. It is not necessary to fast (avoid eating for 12 hours) before testing.

LDL cholesterol — The low density lipoprotein (LDL) cholesterol (sometimes called bad cholesterol) is a more accurate predictor of CHD than total cholesterol. Higher LDL cholesterol concentrations are associated with an increased incidence of CHD in many studies.

Most healthcare providers prefer to measure LDL cholesterol after the person has fasted (not eaten) for 12 to 14 hours. A test to measure LDL in people who have not fasted is also available, although the results may differ slightly from the fasting result.

People with hyperlipidemia should know their own LDL cholesterol level, as well as their goal LDL. This goal depends upon several factors, including the person's history of CHD or CHD risk equivalents and their 10-year risk score of developing CHD.

Ten year risk of developing CHD — The 10-year risk score is based on information from the Framingham Heart Study, a large study that has followed participants, as well as their children and grandchildren, for greater than 50 years. The 10-year risk can be calculated for women (calculator 1) and for men (calculator 2).

Triglycerides — High triglyceride levels are also associated with an increased risk of CHD. Triglyceride levels are divided as follows:

• Normal - less than 150 mg/dL (1.69 mmol/L)
• Borderline high - 150 to 199 mg/dL (1.69 to 2.25 mmol/L)
• High - 200 to 499 mg/dL (2.25 to 5.63 mmmol/L)
• Very high - greater than 500 mg/dL (5.65 mmol/L)

Triglycerides should be measured after fasting for 12 to 14 hours.

HDL cholesterol — Not all cholesterol is bad. Elevated levels of HDL cholesterol actually lower the risk of heart disease. In fact, a very high HDL (greater than or equal to 60 mg/dL or 1.55 mmol/L) is considered a negative risk factor for CHD (removes one risk factor). On the other hand, treatment is sometimes recommended for people with low levels of HDL cholesterol (<40 mg/dL or 1.03 mmol/L), particularly if they already have heart disease.

Similar to total cholesterol, the HDL-cholesterol can be measured on any blood specimen. It is not necessary to be fasting.

CHOLESTEROL SCREENING GUIDELINES

A number of groups have created guidelines for cholesterol screening. The guidelines differ in their recommendations concerning the recommended age to start screening, the time interval between screenings, and the age at which screening may stop.

The United States Preventive Services Task Force recommends the following:

• Lipid screening should start at age 35 in men and age 45 in women. Those at risk for CHD should be treated based upon the results of their screening test.
• Screening is recommended at a younger age (age 20 to 35 in men and 20 to 45 in women) for people with CHD risk factors. These include people with diabetes, a family history of heart disease in male relatives before age 50 or in female relatives before age 60, a family history of hyperlipidemia, or a personal history of multiple CHD risk factors (eg, smoking, high blood pressure).
• Screening should include total cholesterol and HDL-cholesterol levels, and can be measured anytime (with or without fasting).
• The optimal time interval between screenings is uncertain; reasonable options include every five years, with a shorter interval for those with high-normal lipid levels and longer intervals for low-risk individuals with low or normal levels.
• There is no recommendation to stop screening at a particular age.
• Screening may be appropriate in older people who have never been screened, although screening a second or third time is less important in older people because lipid levels are less likely to increase after age 65.

TREATMENT

The treatment options for people with high cholesterol and lipids are discussed separately. (See "Patient information: High cholesterol treatment options".)

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two people are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:
Patient information: High cholesterol treatment options
Patient information: Diabetes mellitus type 1: Overview
Patient information: Diabetes mellitus type 2: Overview
Patient information: Transient ischemic attack
Patient information: Stroke symptoms and diagnosis
Patient information: Claudication (peripheral arterial disease)
Patient information: Abdominal aortic aneurysm
Patient information: High blood pressure in adults

Professional Level Information:
Approach to the patient with hypertriglyceridemia
HDL metabolism and approach to the patient with abnormal HDL-cholesterol levels
Intensity of lipid lowering therapy in secondary prevention of coronary heart disease
Lipid lowering with diet or dietary supplements
Lipid lowering with drugs other than statins and fibrates
Lipid lowering with fibric acid derivatives
Lipid lowering with statins
Lipoprotein(a) and cardiovascular disease
Primary disorders of LDL-cholesterol metabolism
Screening guidelines for dyslipidemia
Secondary causes of dyslipidemia
Treatment of drug-resistant hypercholesterolemia
Treatment of dyslipidemia in the elderly
Treatment of lipids (including hypercholesterolemia) in primary prevention
Treatment of lipids (including hypercholesterolemia) in secondary prevention

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/healthtopics.html)

• National Cholesterol Education Program of the National Heart, Lung, and Blood Institute of the NIH

      (www.nhlbi.nih.gov/chd)

• American Heart Association

      (www.americanheart.org)

• The Hormone Foundation

      (www.hormone.org/public/other.cfm, available in English, Spanish, and Portuguese)

• The Framingham Heart Study

      (www.framingham.com/heart/)

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