Lipoprotein:- Part 3 – Very Low-Density Lipoprotein (VLDL)
Very Low-Density Lipoprotein (VLDL)
Sample for Very Low-Density Lipoprotein (VLDL)
- The best sample is serum after 10 to 12 hours of fasting.
- Plasma can also be used.
- The preservative is stable for one week at 4 °C.
Purpose of the test (Indications) for Very Low-Density Lipoprotein (VLDL)
- These are estimated to predict heart disease.
- Lipoprotein may be part of the lipid profile.
- These are done regularly to monitor the disease.
Precautions for Very Low-Density Lipoprotein (VLDL)
- Keep in mind that smoking and alcohol decrease HDL values.
- After myocardial infarction, the cholesterol level may be decreased.
- HDL values are age and sex depending.
- Drugs that may affect (increase) the lipoproteins are Aspirin, Phenothiazines, Sulfonamides, oral contraceptives, and steroids.
- HDL is raised in Hypothyroidism and decreased in Hypothyroidism.
What are lipoproteins:
- Lipoproteins consist of the following:
- High-density lipoprotein (HDL).
- Low-density lipoprotein (LDL).
- Very low-density lipoprotein (VLDL).
- Chylomicrons
- The outer covering lipoproteins are called Apoproteins, and these are classified into:
- Apo-1.
- Apo-II.
- Apo- B.
- Apo-D.
- Apo-E.
- Apolipoproteins are a hydrophilic component of lipoproteins.
- While lipids like cholesterol and triglycerides are hydrophobic and need to be placed in water-soluble micellar structures (Apolipoproteins) in order to be transported in the plasma.
- Apo-C, B-100, and E become the main components.
Very low-density lipoprotein (VLDL)
- It originates from the liver and carries triglycerides from the liver to other tissues.
- VLDL carries a very small amount of cholesterol.
- It is the product of endogenous lipoprotein synthesis in the liver and is delivered to the tissue.
- VLDL proteins are the main carrier of triglycerides which are synthesized in the liver.
- Triglycerides are derived from dietary precursors, such as free fatty acids, glycerol, and carbohydrates.
- Triglycerides are a predominant component.
- VLDL contains about 10% cholesterol and functionally important apolipoproteins.
- VLDL may be expressed as the percentage of cholesterol.
- The Apo – C activates the release of lipoprotein lipase enzyme, which hydrolyzes triglyceride into glycerol, monoglycerol, and free fatty acids.
- This reaction may give rise to intermediate lipoproteins (IDL).
- VLDL consists of the following:
- Triglycerides = 40% to 60%
- Cholesterol = 5% to 8%
- Cholesterol ester = 11% to 14%
- Phospholipids = 20% to 23%
- Protein = 4% to 11%
- Another source:
- Triglycerides = 60%
- Cholesterol = 15%
- Phospholipids = 15%
- Protein 10%
Composition of the Very Low-Density Lipoprotein (VLDL):
- It is a pre-β-lipoprotein derived from the liver.
Type of lipid | Source | Diameter (nm) | Ultracentrifuge | % Protein | % Total lipids | Free cholesterol |
Very low-density lipoprotein (VLDL) |
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Difference between VLDL and LDL:
- LDL has lower contents of triglycerides and higher cholesterol contents.
- LDL carries 70% of the total cholesterol and very little amount of triglycerides.
- LDL has no apoproteins C or E.
- Inside the cells, the LDL molecule is metabolized into its component parts.
- It shows that LDL has a major role in providing cholesterol to the body cells and leads to atherosclerosis.
- VLDL has the majority of triglycerides and less cholesterol content.
Draw-backs of Very Low-Density Lipoprotein (VLDL):
- VLDL is associated with an increased risk of coronary heart disease.
- VLDL can convert to LDL.
- More than 25% to 50% of Very Low-Density Lipoprotein (VLDL) is associated with increased coronary heart disease.
Functions of Very Low-Density Lipoprotein (VLDL):
- Very Low-Density Lipoprotein (VLDL) has the main role of transporting endogenously synthesized triglycerides by the liver to:
- Adipose tissue.
- Muscles.
- Very Low-Density Lipoprotein (VLDL) carries triglycerides from the intestinal mucosa to the periphery.
- Very Low-Density Lipoprotein (VLDL) is mainly synthesized in the liver and, to a lesser extent, the intestinal tissues.
- Very Low-Density Lipoprotein (VLDL) passes through a transient intermediate lipoprotein form called intermediate-density lipoprotein (IDL).
- Intermediate-density lipoprotein (IDL) changes to Low-density lipoprotein (LDL).
Normal Very Low-Density Lipoprotein (VLDL)
Source 2
- 7 to 32 mg/dL.
Another source
- 25% to 50%
Source 4
Age | mg/dL |
Adult | |
Desirable | <130 |
Borderline to high risk | 140 to 159 |
High risk | >160 |
Children and adolescents | |
Desirable | <110 |
Borderline – high risk | 110 to 129 |
High risk | >130 |
Increased Very Low-Density Lipoprotein (VLDL) is seen in:
- Nephrotic syndrome.
- Glycogen storage diseases.
- Familial LDL lipoproteinemia.
- Hypothyroidism.
- Chronic liver disease.
- Liver cell carcinoma.
- Gammopathies.
- Cushing syndrome.
- Familial hypercholesterolemia.
Decreased Very Low-Density Lipoprotein (VLDL) is seen in:
- Hypoproteinemia.
- Hyperthyroidism.
- Familial hypolipoproteinemia.
Table showing the summary of characteristics of the lipoproteins
Characteristics | Chylomicron | HDL | LDL | VLDL |
Plasma appearance | Creamy layer, slightly turbid | Clear | Clear or yellow-orange tint | Turbid to opaque |
Size (diameter nm) | >70.0 | 4 to 10 | 19.6 to 22.7 | 25 to 70 |
Electrophoretic mobility | Origin | α – region | β – region | Pre – β region |
Molecular weight | 0.4 to 30 x 109 | 3.6 x 109 | 2.75 x 109 | 5 to 10 x 109 |
Synthesized in (Tissue of origin) | Intestine | Intestine and liver | Intravascular | Liver and intestine |
Composition by weight in % | ||||
Cholesterol esterified | 5 | 38 | 49 | 11 to 14 |
Cholesterol unesterified | 2 | 10 | 13 | 5 to 8 |
Triglycerides | 84 | 9 | 11 | 44 to 60 |
Phospholipids | 7 | 22 | 27 | 20 to 23 |
Proteins | 2 | 21 | 23 | 4 to 11 |
Triglycerides | Markedly raised | Normal | Normal/ Raised | Moderately to Markedly raised |
Clinical significance of | Pancreatitis and acute abdomen | Decreased risk of CAD | Increased risk of CAD | Increased risk of CAD |
Functions | Transport dietary lipids to tissue | Carry cholesterol from tissue to liver | Carries cholesterol to tissue | Transport endogenous TG from the liver to adipose tissue |
Note: Lipoproteins are described in detail in LDL and HDL.
Questions and answers:
Question 1: What is the complication of Very Low-Density Lipoprotein (VLDL)?
Question 2: Is Very Low-Density Lipoprotein (VLDL) increased in renal diseases?