INTRODUCTION

Hyperlipidemia refers to increased levels of lipids (fats) in the blood, including cholesterol and triglycerides. Although hyperlipidemia does not cause you to feel bad, it can significantly increase your risk of developing coronary heart disease, also called coronary artery disease or coronary disease. People with coronary disease 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 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 (Beyond the Basics)".)

OTHER RISK FACTORS FOR CORONARY DISEASE

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

The following are coronary disease-risk equivalents; people with these medical problems are thought to be at similar risk for complications of coronary disease as people with known coronary disease.

• Many patients with diabetes mellitus, type 1 and 2 (See "Patient information: Diabetes mellitus type 1: Overview (Beyond the Basics)" and "Patient information: Diabetes mellitus type 2: Overview (Beyond the Basics)".)
• Symptomatic carotid artery disease (eg, stroke or transient ischemia attack) (See "Patient information: Transient ischemic attack (Beyond the Basics)" and "Patient information: Stroke symptoms and diagnosis (Beyond the Basics)".)
• Peripheral artery disease (eg, claudication) (See "Patient information: Peripheral artery disease and claudication (Beyond the Basics)".)
• Abdominal aortic aneurysm (See "Patient information: Abdominal aortic aneurysm (Beyond the Basics)".)
• Kidney disease (See "Patient information: Chronic kidney disease (Beyond the Basics)".)

Other factors that increase the risk of coronary disease include:

• Cigarette smoking
• Hypertension (blood pressure ≥140/90 or use of blood pressure medication) (See "Patient information: High blood pressure in adults (Beyond the Basics)".)
• Family history of coronary disease at a young age in a first degree relative (parents and siblings). In males: first degree relatives under 55 years; in females: first degree relative under 65 years
• Gender: Men have a higher risk of coronary disease than women at every age
• Age: There is an increasing risk of coronary disease with increasing age

LIPID TYPES

The term lipids includes cholesterol and triglycerides. There are many different types of lipid (also called lipoproteins). Blood tests can measure the level of your lipoproteins. The standard lipid blood tests include a measurement of total cholesterol, LDL (low density lipoproteins) and HDL (high density lipoproteins), and triglycerides.

Total cholesterol — A high total cholesterol level can increase your risk of coronary disease. However, decisions about when to treat high cholesterol are usually based upon the level of LDL or HDL cholesterol, rather than the level of total cholesterol.

• A total cholesterol level of less than 200 mg/dL (5.17 mmol/L) is normal.
• A total cholesterol level of 200 to 239 mg/dL (5.17 to 6.18 mmol/L) is borderline high.
• A total cholesterol level greater than or equal to 240 mg/dL (6.21 mmol/L) is high.

The total cholesterol level 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 coronary disease than total cholesterol. Higher LDL cholesterol levels increase your risk of coronary disease.

Most healthcare providers prefer to measure LDL cholesterol after you have not eaten (fasted) 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.

You should know your LDL cholesterol level and your LDL goal. This goal depends upon several factors, including your history of coronary disease or coronary disease-risk equivalents and your 10-year risk score of developing coronary disease.

Ten year risk of developing coronary disease — 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 coronary disease. 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 mmol/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 coronary disease (removes one risk factor). On the other hand, treatment is sometimes recommended for people with low levels of HDL cholesterol (less than 40 mg/dL or 1.03 mmol/L), particularly if they already have coronary disease.

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

Non-HDL cholesterol — Non-HDL cholesterol is calculated by subtracting HDL cholesterol from total cholesterol. Since total cholesterol and HDL cholesterol can be measured without fasting, so can non-HDL cholesterol. Non-HDL cholesterol is a good predictor of cardiovascular risk and is a better predictor of risk than LDL cholesterol in people with type 2 diabetes and in women.

An appropriate non-HDL cholesterol goal can be calculated by adding 30 mg/dL (0.78 mmol/L) to your LDL cholesterol goal. As discussed, the LDL cholesterol goal depends on a number of factors. (See 'LDL cholesterol' above.)

WHEN SHOULD I HAVE MY CHOLESTEROL LEVEL TESTED?

Many expert groups have guidelines for cholesterol screening. The guidelines differ in their recommendations about when to start screening, how frequently you should be screened, and when to stop.

One expert group, the United States Preventive Services Task Force recommends the following:

• Lipid screening should start at age 35 in men without other risk factors for coronary disease and at age 20 to 35 in men with risk factors. These include men with diabetes, a family history of heart disease in a close male relative younger than age 50 or a close female relative younger than age 60, a family history of high cholesterol, or a personal history of multiple coronary disease risk factors (eg, smoking, high blood pressure).
• Lipid screening should definitely start at age 45 and perhaps at age 20 in women with other risk factors for coronary disease. No recommendation for or against screening was made for women without risk factors for coronary disease. UpToDate authors believe that even low risk women should be screened starting at age 45.
• Those at risk for coronary disease should be treated based upon the results of their screening test.
• 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.

HIGH CHOLESTEROL TREATMENTS

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

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient information: Atherosclerosis (The Basics)
Patient information: Coronary heart disease (The Basics)
Patient information: Diabetes and diet (The Basics)
Patient information: The ABCs of diabetes (The Basics)
Patient information: Nonalcoholic steatohepatitis (NASH) (The Basics)
Patient information: Medicines after an ischemic stroke (The Basics)
Patient information: Heart attack recovery (The Basics)
Patient information: Medicines after a heart attack (The Basics)
Patient information: Recovery after coronary artery bypass graft surgery (CABG) (The Basics)
Patient information: Lowering the risk of having another stroke (The Basics)
Patient information: Coronary heart disease in women (The Basics)
Patient information: Can foods or supplements lower cholesterol? (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient information: High cholesterol treatment options (Beyond the Basics)
Patient information: Diabetes mellitus type 1: Overview (Beyond the Basics)
Patient information: Diabetes mellitus type 2: Overview (Beyond the Basics)
Patient information: Transient ischemic attack (Beyond the Basics)
Patient information: Stroke symptoms and diagnosis (Beyond the Basics)
Patient information: Peripheral artery disease and claudication (Beyond the Basics)
Patient information: Abdominal aortic aneurysm (Beyond the Basics)
Patient information: High blood pressure in adults (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

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
Lipoprotein(a) and cardiovascular disease
Inherited disorders of LDL-cholesterol metabolism
Screening guidelines for dyslipidemia
Secondary causes of dyslipidemia
Statins: Actions, side effects, and administration
Treatment of drug-resistant hypercholesterolemia
Treatment of dyslipidemia in the older adult
Treatment of lipids (including hypercholesterolemia) in primary prevention
Treatment of lipids (including hypercholesterolemia) in secondary prevention

The following organizations also provide reliable health information.

• 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/)

[1,2]