Lipids Total

Sample
- This is done on the serum of the patient.
- Fasting samples for 8 to 12 hours is needed.
Indication
- Total lipid is advised to assess lipid metabolism.
- This is helpful for the diagnosis of hyperlipidemia.
Pathophysiology
- Definition: The term lipid is defined as soluble in the organic solvent (such as ether, hexane or chloroform), and insoluble in water.
- These are carbon and hydrogen containing compounds and mostly hydrophobic.
- Lipids are synthesized from dietary fat.
Lipids play an important role in life :
- These are precursor of the hormone
- Help indigestion.
- Provide a store of energy.
- They provide metabolic fuels.
- They are part of the cell membranes.
- Make certain hormones.
- Lipids yield fatty acid on hydrolysis.
- Lipids can form esters.
- Cholesterol and triglycerides are the main types of lipids measured in routine blood chemistry tests.
- Lipids are a group of substances which consists of :
- Glycerol ester includes:
- Triglycerides.
- Diglycerides.
- Monoglycerides. P
- Phosphoglycerides.
- Free fatty acids.
- Phospholipids.
- Sterols include:
- Cholesterol
- Steroid hormone.
- Bile acids.
- Vit.D.
- Carotenoids.
- Vitamins A, E, and K.
- Glycerol ester includes:
- Another classification of Lipids is as follows :
- Neutral fat consists of fatty acids (oleic, linoleic, Stearic, Arachidonic, and Palmitic acids) in the form of triglycerides.
- Waxes.
- Phospholipids :
- Lecithin.
- Cephalins.
- Sphingomyelin.
- Glycolipids :
- Cerebrosides.
- Gangliosides.
- Lipoproteins.
- HDL
- HDL-Cholesterol
- LDL
- LDL-Cholesterol.
- VLDL
- Sterols:
- Cholesterol and esters (major biologic significance).
- Steroids.
- Bile acids.
- Substances associated with lipids:
- Carotenoids.
- Vit.K.
- Vit. E.
- Simple lipids.
- Neutral fats.
- Waxes.
- Phospholipids.
- Compound Lipids.
- Glycolipids:
- Cerebrosides.
- Gangliosides.
- Lipoproteins.
- Glycolipids:
- Lipid-associated substances are :
- Triacylglycerols are the major component of most foods, typically making up more than 95 to 99% of the total lipids.
- Cholesterol and triglycerides are the main types of lipids measured in routine blood chemistry.
- Conjugated lipids are with the combination of phosphate or sugar to lipid molecules.
- Lipids 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.
- As these are water-insoluble so these are carried by the proteins.
- Free fatty acids are the very small amount of the blood and these are bound to a loose complex with albumin.
- Major lipid components in the plasma found are triglycerides, Cholesterol, and phospholipids.
- These are transported in the blood as lipoproteins with large molecules of proteins as apolipoproteins.
- The largest and least dense molecule of lipoprotein is Chylomicron and this followed by:
- Very low-density lipoprotein (VLDL).
- Low-density lipoproteins (LDL).
- Intermediate density lipoproteins (IDL).
- High-density lipoproteins (HDL).
- Most of the triglycerides of non-fasting plasma reside in the chylomicrons.
- While fasting plasma sample triglycerides are mostly VLDL.
- Most of the cholesterol is present in LDL.
- A small fraction of the cholesterol 15 to 25% is in HDL.
- Triacylglycerols are esters of three fatty acids and a glycerol molecule.
- The terms fat, oil, and lipid are often used interchangeably.
- Hyperlipidemia is the presence of elevated or abnormal levels of lipids and/or lipoproteins in the blood.
- The peak level of raise lipids (Hyperlipemia) occurs after 3 to 6 hours after the meal.
- Plasma cholesterol level increases with age.
- In the latter half of the pregnancy, plasma cholesterol is raised about 30% of the women’s normal level.
- Men’s cholesterol level is higher than in women.
- Lipids and lipoproteins are a highly modifiable risk factor for cardiovascular disease.
- One of the most clinically relevant lipid substances is cholesterol, especially for atherosclerosis and cardiovascular disease.
- Hyperlipoproteinemia is elevated levels of lipoproteins.
Functions of lipids
- The main biological function of lipids is store energy.
- Lipids form structural components of the cell membrane.
- Lipids form messenger and signaling molecules.
- Lipids can easily be stored in the body and work as a source of energy.
Raised level of Lipids is seen in:
- In hypothyroidism, both free and ester-cholesterol is raised.
- In nephrotic syndrome, β-lipoprotein is greatly raised. Total plasma lipids exceed 2 g/dL. The plasma is milky.
- In lipoid nephrosis, a total cholesterol level is 300 to 1000 mg/dL.
- These are raised in Ketosis, generally in the untreated Diabetes mellitus. The plasma lipid level ranges from 0.7 to 2.0 g/dL.
- In diabetes mellitus, the level reported is reached 22 g/dL.
Now to assess the total lipids mostly Cholesterol, Triglycerides, LDL, HDL is advised.