Lipoprotein disorders
| Lipoprotein disorders | ||
| ICD-10 | E78 | |
|---|---|---|
| ICD-9 | 272 | |
| MeSH | C18.452.339 | |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: Dyslipidemia, dyslipoproteinemia, hyperlipidemia
Overview
Lipoproteins, which are aggregates of proteins and lipids, allow the circulation of hydrophobic lipids in the body. Disorders of lipids and lipoproteins metabolism have important health consequences, mainly on the cardiovascular system. Lipoprotein disorders can be described as abnormalities in the level of the lipids, which include cholesterol and triglycerides, or as abnormalities in the levels of lipoproteins that include LDL, HDL, VLDL and chylomicrons.
Lipoprotein disorders have been initially classified in 1967 into different phenotypes by Fredrickson according to the type of lipoproteins that accumulate. However; Fredrickson's classification of hyperlipoproteinemias took into consideration the elevation in chylomicrons, LDL, VLDL but did not include abnormalities in HDL levels. Other classifications have been suggested, one of which is the National Cholesterol Education Program (NCEP) classification of lipoprotein disorders. NCEP classifies lipid disorders according to laboratory cut off points for the levels of total cholesterol, LDL-C and HDL.
Lipoprotein disorders can be classified according to different criteria. First of all, lipoprotein disorders can be classified as primary disorders resulting from genetic mutations and secondary to other diseases. Another way of classifying lipoprotein disorders is as hypolipidemia (or hypolipoproteinemia) and hyperlipidemia (hyperlipoproteinemia) where the lipoprotein levels are decreased and increased respectively. However, the latter classification is not precise and creates some ambiguity, because some people can be labeled as having hyperlipidemia but have simultaneously high level of some lipoproteins and low levels of other lipoproteins depending on the underlying pathophysiology. Hence, a better term to describe the constellation of abnormal lipid profiles is "disorders of lipoproteins", or dyslipoproteinemia or dyslipidemia.
Classification
There are two major ways in which dyslipidemias are classified:
- Phenotype, or the presentation in the body (including the specific type of lipid that is increased)
- Etiology, or the reason for the condition (genetic, or secondary to another condition.) This classification can be problematic, because most conditions involve the intersection of genetics and lifestyle issues. However, there are a few well defined genetic conditions that are usually easy to identify.
Algorithm
| Dyslipidemia | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Hypolipidemia | Hyperlipidemia | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Familial combined hypolipidemia | Abetalipoproteinemia (Bassenn-Kornzweig syndrome) | Primary hyperlipidemia | Secondary hyperlipidemia | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fredrickson classification | Alcoholism Anorexia nervosa Diabetes Drugs Nephrotic syndrome Obesity Renal insufficiency Thyroid disease | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Type I: Familial hyperchylomicronemia | Type II | Type III: Dysbetalipoproteinemia | Type IV: Familial hypertriglyceridemia | Type V: Familial mixed hypertriglycerideimia | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Type A: Familial hypercholesterolemia | Type B: Familial combined hyperlipidemia | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Type A | Type B | Type C | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Types
Increases
- Hyperlipoproteinemia: lipoproteins (usually LDL unless otherwise specified)
- Hyperchylomicronemia: chylomicrons
- Combined hyperlipidemia: both LDL and triglycerides
- Familial hypercholesterolemia is a specific form of hypercholesterolemia due to a defect on chromosome 19 (19p13.1-13.3).
Decreases
- Hypolipoproteinemia: lipoproteins
- Hypocholesterolemia: cholesterol
- Abetalipoproteinemia: beta lipoproteins
- Tangier disease: high density lipoprotein