Lipids Total

What sample is needed for Lipids Total?

1. This is done on the patient’s serum.
2. Fasting samples for 8 to 12 hours are needed.

What are the indications for Lipids Total?

1. Total lipid is advised to assess lipid metabolism.
2. It is helpful for the diagnosis of hyperlipidemia.

How will you define Lipids?

1. Lipids are carbon- and hydrogen-containing compounds that are hydrophobic: insoluble in water and soluble in organic solvents.
2. Biologically, groups are:
   1. Neutral fats (consists of fatty acids, primarily oleic acid, linoleic acid, stearic, arachidonic, and palmitic acid).
   2. Conjugated lipids.
   3. Sterols (biologically active cholesterol).
3. The lipids are a heterogeneous group of compounds related more by their physical characteristics than their chemical properties.
4. The lipids have the common properties:
   1. Relatively insoluble in water.
   2. Soluble in nonpolar solvents like ether, benzene, and alcohol.
5. Lipids are essential dietary constituents due to their importance of:
   1. Fat-soluble vitamins.
   2. High energy.
   3. Essential fatty acids are present in natural foods.
6. Lipids include fats, oils, steroids, waxes, and related compounds.
7. The major lipids are:
   1. Cholesterol.
   2. Triglycerides.
   3. Phospholipid.

What is the importance of lipids in our body?

1. Lipids serve as an efficient source of energy when stored in adipose tissue.
2. Lipids serve as thermal insulators in the subcutaneous tissues and organs.
3. Nonpolar lipids act as an electrical insulator, allowing the rapid progression of depolarization waves along myelinated nerves.
4. The fat contents of the nerve tissue are high.
5. The combination of lipids and protein as lipoproteins are important cellular constituents.
6. It is part of the cell membranes and mitochondria within the cytoplasm.
7. It is a means of transporting lipids in the blood.
8. Lipids are important to understanding atherosclerosis, obesity, and polyunsaturated fatty acids in nutrients and health.

What are the properties of lipids?

1. Lipids are soluble in organic solvents (ether, hexane, or chloroform) and insoluble in water.
   1. These are carbon and hydrogen-containing compounds and are mostly hydrophobic.
   2. Lipids are insoluble in liquid media like plasma. Therefore, these must be packaged into lipoprotein particles.
   3. Lipids have a hydrophilic exterior with the help of a phospholipids coat.
   4. The phospholipid layers have various types of apolipoproteins.
   5. In the central part of lipoproteins are cholesterol and triglycerides.
   6. Every lipoprotein contains:
      1. Cholesterol.
      2. Triglycerides.
      3. Phospholipids.
      4. Apolipoproteins

How will you discuss the metabolism of lipids?

1. Lipids are synthesized from dietary fat.
2. Ingested lipids are taken up by the intestinal epithelial cells and packaged into lipoproteins called chylomicrons.
3. Chylomicron is the lipoprotein that transports lipids from the intestinal epithelium to other somatic cells, particularly liver cells, where these are endocytosed via apolipoprotein E.
4. In the liver, cholesterol and triglycerides are packed into another type of lipoprotein called  Very low-density lipoprotein  (VLDL), which is secreted into the blood.
   1. VLDL has increased amount of Triglycerides (TG).  VLDL is the mean for the transport of TG to the other somatic cells.
   2. Hepatocytes also produce high-density lipoproteins (HDL).

Lipids total: Lipid metabolism

What is the difference between Chylomicron and VLDL?

Cholesterol sources

Cholesterol absorption

What is the important role of Lipids in life?

1. These are precursors of the hormone.
2. Help indigestion.
3. Provide a store of energy.
4. They provide metabolic fuels.
5. They are part of the cell membranes.
6. Make certain hormones.
7. Lipids yield fatty acids on hydrolysis.
8. Lipids can form esters.
9. Cholesterol and triglycerides are the main lipids measured in routine blood chemistry tests.

Cholesterol metabolism

How will you classify lipids?

Lipids are a group of substances that consist of :

1. Glycerol ester includes:
   1. Triglycerides.
   2. Diglycerides.
2. Monoglycerides.
   1. Phosphoglycerides.
3. Free fatty acids.
4. Phospholipids.
5. Sterols include:
   1. Cholesterol
   2. Steroid hormone.
   3. Bile acids.
   4. Vit.D.
6. Carotenoids.
7. Vitamins A, E, and K.

Another classification of Lipids is as follows :

1. Neutral fat consists of fatty acids (oleic, linoleic, Stearic, Arachidonic, and Palmitic acids) in triglycerides.
2. Waxes.
3. Phospholipids :
   1. Lecithin.
   2. Cephalins.
   3. Sphingomyelin.
4. Glycolipids :
   1. Cerebrosides.
   2. Gangliosides.
5.  Lipoproteins.
   1. HDL
   2. HDL-Cholesterol
   3. LDL
   4. LDL-Cholesterol.
   5. VLDL
6.  Sterols:
   1. Cholesterol and esters (major biological significance).
   2. Steroids.
   3. Bile acids.
7. Substances associated with lipids:
   1. Carotenoids.
   2. Vit. K.
   3. Vit. E.
8. Lipids may be classified as:
   1. Simple lipids.
      1. Neutral fats.
      2. Waxes.
   2. Complex Lipids.
      1. Phospholipids.
      2.  Glycolipids:
         1. Cerebrosides.
         2. Gangliosides.
   3. Lipoproteins.
9. Lipid-associated substances are :
   1. Triacylglycerols are the major component of most foods, typically making up more than 95 to 99% of the total lipids.
   2. Cholesterol and triglycerides are the main lipids measured in routine blood chemistry.
   3. Conjugated lipids are the combination of phosphate or sugar to lipid molecules.

Cholesterol

1. It is the best-known steroid, and it has an association with atherosclerosis.
   1. Cholesterol is the precursor of other important steroids, such as bile acids, adrenocortical hormones, sex hormones, vitamin D, cardiac glycosides, plant sitosterol, and some alkaloids.
   2. Cholesterol is distributed in almost all of the body cells. It is abundant in the nervous tissue.
   3. It is the main component of lipoproteins.
   4. It is a major part of the cell membranes.
   5. It is found in animal fats but not plant fats.

Lipids on thin-layer chromatography show the following pattern:

Lipids thin layer chromatography

Lipids as lipoproteins with their properties:

What are the important Facts about lipids?

1. Lipids are carried in the blood by special proteins made in the liver. The two main forms of protein-bound cholesterol are called LDL and HDL cholesterol.
   1. As these are water-insoluble, so they are carried by the proteins.
   2. Free fatty acids are a very small amount of the blood, bound to a loose complex with albumin.
   3. Major lipid components in the plasma are triglycerides, Cholesterol, and phospholipids.
   4. These are transported in the blood as lipoproteins with large molecules of proteins as apolipoproteins.
   5. The largest and least dense molecule of lipoprotein is Chylomicron, and this is followed by:
      1. Very low-density lipoprotein (VLDL).
      2. Low-density lipoproteins (LDL).
      3. Intermediate density lipoproteins (IDL).
      4. High-density lipoproteins (HDL).
   6. Most of the triglycerides of non-fasting plasma reside in the chylomicrons.
   7. While fasting plasma sample triglycerides are mostly VLDL.
   8. Most of the cholesterol is present in LDL.
   9. A small fraction of the cholesterol, 15 to 25%, is in HDL.
2. Triacylglycerols are esters of three fatty acids and a glycerol molecule.

Lipid absorption

3. The terms fat, oil, and lipid are often used interchangeably.

How will you define Hyperlipidemia?

1. It is the presence of elevated or abnormal levels of lipids and lipoproteins in the blood.
2. 1. The peak level of raised lipids (Hyperlipemia) occurs 3 to 6 hours after the meal.
   2. Plasma cholesterol levels increase with age.
   3. In the latter half of the pregnancy, plasma cholesterol is raised by about 30% of the women’s normal level.
   4. Men’s cholesterol level is higher than women’s.
3. Lipids and lipoproteins are highly modifiable risk factors for cardiovascular disease.
4. One of the most clinically relevant lipid substances is cholesterol, especially in atherosclerosis and cardiovascular disease.
5. Hyperlipoproteinemia is elevated levels of lipoproteins.

What are the Functions of lipids?

1. The main biological function of lipids is to store energy.
2. Lipids form structural components of the cell membrane.
3. Lipids form messenger and signaling molecules.
4. Lipids can easily be stored in the body and work as a source of energy.
   

   Lipids function

When will you see the raised level of Lipids?

1. In hypothyroidism, both free and ester-cholesterol are increased.
2. In nephrotic syndrome, β-lipoprotein is significantly raised. Total plasma lipids exceed 2 g/dL, and the plasma is milky.
3. The total cholesterol level of lipoid nephrosis is 300 to 1000 mg/dL.
4. These are raised in Ketosis, generally in untreated Diabetes mellitus. The plasma lipid level ranges from 0.7 to 2.0 g/dL.
5. In diabetes mellitus, the level reported reached 22 g/dL.

Now, assess the total lipids, mostly Cholesterol, Triglycerides, LDL, and HDL are advised.

Questions and answers: