Trigylycerides PDF

CLINICAL CHEMISTRY Trigylycerides Introduction A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids.There are many triglycerides: depending on the oil source, some are highly unsaturated, some less so.Saturated compo...

CLINICAL CHEMISTRY Trigylycerides Introduction A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids.There are many triglycerides: depending on the oil source, some are highly unsaturated, some less so.Saturated compounds are "saturated" with hydrogen — all available places where hydrogen atoms could be bonded to carbon atoms are occupied. Unsaturated compounds have double bonds (C=C) between carbon atoms, reducing the number of places where hydrogen atoms can bond to carbon atoms. Saturated compounds have single bonds (C-C) between the carbon atoms, and the other bond is bound to hydrogen atoms (for example =CH-CH=, -CH2-CH2-, etc.).Unsaturated fats have a lower melting point and are more likely to be liquid. Saturated fats have a higher melting point and are more likely to be solid.Triglycerides are the main constituents of vegetable oil (typically more unsaturated) and animal fats (typically more saturated). In humans, triglycerides are a mechanism for storing unused calories, and their high concentration in blood correlates with the consumption of starchy and other high carbohydrate foods. Clinical Significance Determination of serum triglyceride concentration is used to assess the possible presence of hypertriglyceridemia (increased blood and serum levels of triglycerides). An elevated level of serum triglycerides increases blood viscosity and precipitates platelet aggregation, which in turn results in diminished vascular flow. In addition, increased triglyceride concentrations in the blood coincide with decreased levels of HDL-cholesterol. Patients with ischemic vascular diseases frequently have elevated serum concentration of triglycerides. 1) Physiologic changes in triglyceride concentration The intake of fatty meal normally entails an increase in the serum concentration of triglycerides. Highest values are measured 6 hours postprandially. 2) Pathologic changes in triglyceride concentration PATIENT PREPARATION BLOOD DRAWING TECHNIQUE  CLINICAL CHEMISTRY SPECIMEN TYPE, COLLECTION AND STORAGE 12 hours fasting, 2-3 ml clotted blood or 2 ml EDTA blood , avoid haemolysis. Serum should be separated from cells as early as possible. Specimen preferably be analyzed on the day of 0 0 collection. Serum is stable for 4 days at 4 C, for 3 months at -20 C and for many years at -70 0 C. As referral sample send about 0.5 ml clear serum, kept cool, to reach destination within 24 hours. APPARATUS AND GLASSWARES APPARATUS: Spectrophotometer at wavelength 500 nm 0 Water bath at 37 C Vortex mixer GLASSWARE: Test tubes Automatic micropipette 10 μl Automatic pipette 1000μl Semi micro cuvette (capacity =1ml) REAGENTS The reagents provided are ready to use. Other Methods 1. Colorimetric Method Example: Van Handel and Silversmith – serum lipids are extracted with Folch’s reagent ( chloroform-ethanol mixture) and phospholipids are removed by adsorption with zeolite, TAG are then saponified using alcoholic KOH to release glycerol and fatty acids. The glycerol is oxidized with periodic acids to produce formaldehyde. A blue colored compound of unknown compositions is formed when formaldehyde is treated with a sulfuric acid solution of chromatrophic acid. 2. Flourometric Method Example: Hantzch Condensation Method 3. Eznymatic Method Example: Glycerol Kinase Method