Hypercholesterolemia
Hypercholesterolemia, also called high cholesterol, is the presence of high levels of cholesterol in the blood.[1] It is a form of hyperlipidemia (high levels of lipids in the blood), hyperlipoproteinemia (high levels of lipoproteins in the blood), and dyslipidemia (any abnormalities of lipid and lipoprotein levels in the blood).[1]
Hypercholesterolemia
Hypercholesterolaemia, high cholesterol
Atherosclerosis, thrombosis, embolism, heart attack, stroke, coronary thrombosis, fat embolism, cardiovascular and coronary heart disease
Poor diet, junk food, fast food, diabetes, alcoholism, monoclonal gammopathy, dialysis therapy, nephrotic syndrome, hypothyroidism, Cushing's syndrome, anorexia nervosa
Elevated levels of non-HDL cholesterol and LDL in the blood may be a consequence of diet, obesity, inherited (genetic) diseases (such as LDL receptor mutations in familial hypercholesterolemia), or the presence of other diseases such as type 2 diabetes and an underactive thyroid.[1]
Cholesterol is one of three major classes of lipids produced and used by all animal cells to form membranes. Plant cells manufacture phytosterols (similar to cholesterol), but in rather small quantities.[2] Cholesterol is the precursor of the steroid hormones and bile acids. Since cholesterol is insoluble in water, it is transported in the blood plasma within protein particles (lipoproteins). Lipoproteins are classified by their density: very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), low density lipoprotein (LDL) and high density lipoprotein (HDL).[3] All the lipoproteins carry cholesterol, but elevated levels of the lipoproteins other than HDL (termed non-HDL cholesterol), particularly LDL-cholesterol, are associated with an increased risk of atherosclerosis and coronary heart disease.[4] In contrast, higher levels of HDL cholesterol are protective.[5]
Avoiding trans fats and replacing saturated fats in adult diets with polyunsaturated fats are recommended dietary measures to reduce total blood cholesterol and LDL in adults.[6][7] In people with very high cholesterol (e.g., familial hypercholesterolemia), diet is often not sufficient to achieve the desired lowering of LDL, and lipid-lowering medications are usually required.[8] If necessary, other treatments such as LDL apheresis or even surgery (for particularly severe subtypes of familial hypercholesterolemia) are performed.[8] About 34 million adults in the United States have high blood cholesterol.[9]
Screening method[edit]
The U.S. Preventive Services Task Force in 2008 strongly recommends routine screening for men 35 years and older and women 45 years and older for lipid disorders and the treatment of abnormal lipids in people who are at increased risk of coronary heart disease. They also recommend routinely screening men aged 20 to 35 years and women aged 20 to 45 years if they have other risk factors for coronary heart disease.[45] In 2016 they concluded that testing the general population under the age of 40 without symptoms is of unclear benefit.[46][47]
In Canada, screening is recommended for men 40 and older and women 50 and older.[48] In those with normal cholesterol levels, screening is recommended once every five years.[49] Once people are on a statin further testing provides little benefit except possibly to determine compliance with treatment.[50]
In the UK, after someone is diagnosed with familial hypercholesterolemia, clinicians, family, or both, contact first- and second-degree relatives to come forward for testing and treatment. Research suggests that clinician-only contact results in more people coming forward for testing.[51][52]
Epidemiology[edit]
Rates of high total cholesterol in the United States in 2010 are just over 13%, down from 17% in 2000.[89]
Average total cholesterol in the United Kingdom is 5.9 mmol/L, while in rural China and Japan, average total cholesterol is 4 mmol/L.[10] Rates of coronary artery disease are high in Great Britain, but low in rural China and Japan.[10]
Research directions[edit]
Gene therapy is being studied as a potential treatment.[90][91]