Hyperlipidemia/ja: Difference between revisions

Treatment include diet control, [[fibrate]]s and niacins. [[Statin]]s are not better than fibrates when lowering triglyceride levels.

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==== Type V ====

{{anchor|type V}}Hyperlipoproteinemia type V, also known as mixed hyperlipoproteinemia familial or mixed hyperlipidemia, is very similar to type I, but with high [[VLDL]] in addition to chylomicrons.

The elevated triglyceride levels (>5&nbsp;mmol/L) are generally due to an increase in very low density lipoprotein (VLDL), a class of lipoprotein prone to cause atherosclerosis.

==== Unclassified familial forms ====

* [[Hyperalphalipoproteinemia]]

* [[Polygenic hypercholesterolemia]]

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=== Acquired (secondary) ===

Acquired hyperlipidemias (also called secondary dyslipoproteinemias) often mimic primary forms of hyperlipidemia and can have similar consequences. They may result in increased risk of premature [[atherosclerosis]] or, when associated with marked [[hypertriglyceridemia]], may lead to [[pancreatitis]] and other complications of the [[chylomicronemia syndrome]]. The most common causes of acquired hyperlipidemia are:

* [[Diabetes mellitus]]

* Use of drugs such as [[thiazide diuretics]], [[beta blockers]], and [[estrogens]]

* [[Hypothyroidism]]

* [[Kidney failure]]

* [[Nephrotic syndrome]]

* [[Alcohol consumption]]

* Some rare [[endocrine disorder]]s and [[metabolic disorders]]

==Presentation==

=== Relation to cardiovascular disease ===

Hyperlipidemia predisposes a person to [[atherosclerosis]]. Atherosclerosis is the accumulation of lipids, cholesterol, calcium, fibrous plaques within the walls of arteries. This accumulation narrows the blood vessel and reduces blood flow and oxygen to muscles of the heart. Over time fatty deposits can build up, hardening and narrowing the arteries until organs and tissues don't receive enough blood to properly function.  If arteries that supply the heart with blood are affected, a person might have [[angina]] (chest pain). Complete blockage of the artery causes infarction of the myocardial cells, also known as [[Myocardial infarction|heart attack]]. Fatty buildup in the arteries can also lead to [[stroke]], if a blood clot blocks blood flow to the brain.

== Screening ==

Adults 20 years and older should have the cholesterol checked every four to six years. Serum level of  [[Low-density lipoprotein|Low Density Lipoproteins]] (LDL) cholesterol, [[High-density lipoprotein|High Density Lipoproteins]] (HDL) Cholesterol, and [[triglyceride]]s are commonly tested in primary care setting using a lipid panel. Quantitative levels of lipoproteins and triglycerides contribute toward [[cardiovascular disease]] risk stratification via models/calculators such as [[Framingham Risk Score]], ACC/AHA Atherosclerotic Cardiovascular Disease Risk Estimator, and/or Reynolds Risk Scores. These models/calculators may also take into account of family history (heart disease and/or high blood cholesterol), age, gender, Body-Mass-Index, medical history (diabetes, high cholesterol, heart disease), high sensitivity [[C-reactive protein|CRP]] levels, coronary artery calcium score, and [[Ankle–brachial pressure index|ankle-brachial index]]. The cardiovascular stratification further determines what medical intervention may be necessary to decrease the risk of future cardiovascular disease.

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=== Total cholesterol ===

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=== LDL cholesterol ===

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=== HDL cholesterol ===

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HDL, also known as "good cholesterol", is associated with decreased risk of cardiovascular disease. HDL cholesterol carries cholesterol from other parts of the body back to the liver and then removes the cholesterol from the body. It can be affected by acquired or genetic factors, including tobacco use, [[obesity]], inactivity, hypertriglyceridemia, [[diabetes]], high carbohydrate diet, medication side effects ([[Beta blocker|beta-blockers]], androgenic steroids, corticosteroids, progestogens, [[thiazide]] diuretics, [[retinoic acid]] derivatives, oral estrogens, etc.) and genetic abnormalities (mutations ApoA-I, LCAT, ABC1). Low level is defined as less than 40 mg/dL.

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=== Triglycerides ===

Triglyceride level is an independent risk factor for cardiovascular disease and/or [[metabolic syndrome]]. Food intake prior to testing may cause elevated levels, up to 20%. Normal level is defined as less than 150 mg/dL. Borderline high is defined as 150 to 199 mg/dL. High level is between 200 and 499 mg/dL. Greater than 500 mg/dL is defined as very high, and is associated with [[pancreatitis]] and requires medical treatment.

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=== Screening age ===

Health organizations does not have a consensus on the age to begin screening for hyperlipidemia. The CDC recommends cholesterol screenings once between ages 9 and 11, once again between 17 and 21, and every 4 to 6 years in adulthood. Doctors may recommend more frequent screenings for people with a family history of early heart attacks, heart disease, or if a child has obesity or diabetes. [[United States Preventive Services Task Force|USPSTF]] recommends men older than 35 and women older than 45 to be screened. NCE-ATP III recommends all adults older than 20 to be screened as it may lead potential lifestyle modification that can reduce risks of other diseases.  However, screening should be done for those with known CHD or risk-equivalent conditions (e.g. [[Acute coronary syndrome|Acute Coronary Syndrome]], history of heart attacks, Stable or Unstable [[angina]], [[Transient ischemic attack]]s, [[Peripheral artery disease|Peripheral arterial disease]] of atherosclerotic origins, coronary or other arterial revascularization).

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=== Screening frequency ===

Adults 20 years and older should have the cholesterol checked every four to six years, and most screening guidelines recommends testing every 5 years. [[United States Preventive Services Task Force|USPSTF]] recommends increased frequency for people with elevated risk of CHD, which may be determined using cardiovascular disease risk scores.

== Management ==

{{main|Lipid-lowering agent}}

Management of hyperlipidemia includes maintenance of a normal body weight, increased physical activity, and decreased consumption of refined carbohydrates and simple sugars. [[Prescription drug]]s may be used to treat some people having significant [[risk factor]]s, such as [[cardiovascular disease]], LDL cholesterol greater than 190 mg/dL or diabetes. Common medication therapy is a [[statin]].

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=== HMG-CoA reductase inhibitors ===

Competitive inhibitors of [[HMG-CoA reductase]], such as lovastatin, atorvastatin, fluvastatin, pravastatin, simvastatin, rosuvastatin, and pitavastatin, inhibit the synthesis of [[mevalonate]], a precursor molecule to cholesterol. This medication class is especially effective at decreasing elevated LDL cholesterol. Major [[side effect]]s include elevated [[transaminase]]s and [[myopathy]].

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=== Fibric acid derivatives ===

Fibric acid derivatives, such as [[gemfibrozil]] and [[fenofibrate]], function by increasing the lipolysis in adipose tissue via activation of peroxisome proliferator-activated receptor-α. They decrease VLDL – [[very low density lipoprotein]] – and LDL in some people.  Major side effects include rashes, GI upset, myopathy, or increased transaminases.

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=== Niacin ===

Niacin, or vitamin B₃ has a mechanism of action that is poorly understood, however it has been shown to decrease LDL cholesterol and triglycerides, and increase HDL cholesterol.  The most common side effect is flushing secondary to [[skin]] [[vasodilation]]. This effect is mediated by [[prostaglandin]]s and can be decreased by taking concurrent [[aspirin]].

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=== Bile acid binding resins ===

[[Bile acid]] binding [[resin]]s, such as [[colestipol]], [[cholestyramine]], and [[colesevelam]], function by binding bile acids, increasing their excretion. They are useful for decreasing LDL cholesterol. The most common side effects include bloating and diarrhea.

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=== Sterol absorption inhibitors ===

Inhibitors of intestinal [[sterol]] absorption, such as [[ezetimibe]], function by decreasing the absorption of cholesterol in the GI tract by targeting [[NPC1L1]], a [[transport protein]] in the [[gastrointestinal wall]]. This results in decreased LDL cholesterol.