Determination of the blood glucose concentration Ms Nadia

Determination of the blood glucose concentration Ms. Nadia Amara

Determination of the blood glucose concentration : • Glucose is the main sugar that the body makes from the food in the diet. It is carried through the bloodstream to provide energy to all cells in the body. • Glucose is a simple sugar (a monosaccharide). The body produces it from protein, fat and, in largest part, carbohydrate. • Ingested glucose is absorbed directly into the blood from the intestine and results in a rapid increase in blood glucose.

Two Methods of Measuring Blood Glucose Level : 1. Reduction method, which is based on the ability of glucose to reduce Cu++ to Cu+ less sensitive, substances that could reduce Cu++ : fructose, galactose, vitamin C, uric acid, etc. 2. Enzymatic method (more specific and precise result) : Glucose is oxidized by glucose oxidase gluconic acid + H 2 O 2 red dye.

Principle of the test : • Glucose present in the plasma is oxidized by the enzyme (Glucose oxidase) to gluconic acid with the liberation of hydrogen peroxide, which is converted to water and oxygen by the enzyme peroxidase. • 4 -aminophenazone , an oxygen acceptor, takes up the oxygen and together with phenol forms Red colored complex which can be measured at 500 nm.

• Procedure : • Centrifuge 3 ml EDTA blood, 2000 rpm for 10 min. The plasma will be separated from the blood cells. Use plasma for sample. • Pipette into each of the three reaction tubes according to the following table

• Mix the content of each tube well, then incubate them at 37 o. C for 10 minutes. • Using cuvette tube, read the sample and standard absorbance against the blank at 500 nm. Calculation: Calculate the concentration of BL in the provided fasting blood samples using the absorbance reading of standard glucose and applying the following equation: Glucose (mg/dl) = (Abs. sample/Abs. standard)* standard conc. (100 mgdl). Normal Range : Normal (fasting BSL = 70 – 110 mg/dl)

Notes : 1. By this method the blood glucose level can be measured linearly up to 500 mg/dl. 2. If the blood glucose level is higher than 500 mg/dl, dilute the plasma three times by adding 2 volumes of normal saline, then repeat the procedure. Multiply the result *3. The color produced will be stable for 2 hours.