Biochemistry: Determination of Serum Triglyceride (Almaaqal University PDF)

Almaaqal University Biochemistry DETERMINATION OF SERUM TRIGLYCERIDE Dr/ Wael Sobhy Darwish Biochemistry PhD  TRIGLYCERIDES  Triglycerides are the main lipids present in human plasma; the others are cholesterol, ph...

Almaaqal University Biochemistry DETERMINATION OF SERUM TRIGLYCERIDE Dr/ Wael Sobhy Darwish Biochemistry PhD  TRIGLYCERIDES  Triglycerides are the main lipids present in human plasma; the others are cholesterol, phospholipids, and non-esterified fatty acids. Triglycerides are synthesized in the intestinal mucosa by the esterification of glycerol and free fatty acids. Triglycerides are the main storage lipids in humans, where they constitute about 95% of adipose tissue lipids  When is it requested? Lipid profile, including triglycerides, is commonly tested when you reach the age of 40, If you have risk factors for cardiovascular disease such as: Family history of high cholesterol or heart disease in close relatives. Being overweight or obese. Diabetes mellitus High blood pressure (hypertension) Smoking cigarettes  Test Preparation Needed? Previously, fasting for 12 hours was recommended, as triglycerides increase after a meal for several hours.  However, studies now show that readings after a meal are just as useful as fasting levels.  ASSAY PRINCIPLE It was determined by enzymatic hydrolysis with lipase enzyme according to the following reactions: The absorbance of rosy-colored Quinoneimine which is proportionate to TG concentration in the sample was measured spectrophotometrically at λ=500 nm.  PROCEDURE 1. Assay conditions: Wavelength: 500 nm (500-550) Cuvette: 1 cm light path Temperature: 37ºC /15-25ºC Sample The patient should be fasting for 10 to 14 hours before sampling. The best specimen is unhemolysed serum, and should be analyzed on the day of collection. Specimens are stable for 7 days when stored at 4C; several months at –20C and for years at –70C  PROCEDURE Blank Standard Sample WR(mL) 1.0 1.0 1.0 Standard (µL) -- 10 -- Sample (µL) -- -- 10 Mix and incubate for 5 min. at 37ºC or 10 min. at room temperature Read the absorbance (A) of the samples and Standard, against the Blank. The colour is stable for at least 60 minutes  Calculations: TG concentration (mg/dL) = x concentration of standard Conversion factor: mg/dl x 0.0114 = mmol/l Expected Value Males: 40 – 160 mg/dl Females: 35 – 135 mg/dl For the recognition of the risk factor hyper-triglyceridemia. Suspicious >150 mg/dl Elevated >200 mg/dl  What does the result mean  Elevated levels of triglycerides have been associated with a high risk of severe atherosclerosis. High triglyceride levels and hyperlipidemia in general can be an inherited trait or can be secondary to disorders including diabetes mellitus, nephrosis, biliary obstruction, and metabolic disorders associated with endocrine disturbances. Having high triglycerides can also lead to a serious medical condition called pancreatitis  What causes high triglyceride? There are many factors which can cause high triglycerides. Examples include a high fat or high sugar diet, high intake of alcohol, obesity and diabetes. There are also genetic factors that increase triglyceride levels. Lifestyle changes can therefore be very effective in reducing triglyceride levels  Drug treatments are also available if lifestyle changes are insufficient.  If there any thing else I should know If you are diabetic and your blood glucose concentrations are out of control, triglyceride concentrations will be very high. Triglyceride levels in the blood may change dramatically after a meal. Even fasting levels vary considerably from day to day. Because of the day to day variation modest changes in fasting triglycerides measured on different days are not considered to be unusual or abnormal. The only acceptable anticoagulants are heparin and EDTA.