Quantitative Determination of Glucose PDF

Biochemistry Quantitative Determination of Glucose Dr/ Wael Sobhy Darwish Biochemistry PhD  Overview Glucose is a major source of energy for most cells. Insulin facilitates glucose entry into the cells. Diabetes (hyperglycemia) results from an inabi...

Biochemistry Quantitative Determination of Glucose Dr/ Wael Sobhy Darwish Biochemistry PhD  Overview Glucose is a major source of energy for most cells. Insulin facilitates glucose entry into the cells. Diabetes (hyperglycemia) results from an inability of insulin to be produced or secreted. Dietary carbohydrate is digested in the gastrointestinal tract to simple monosaccharides, which are then absorbed. The blood glucose concentration, as always as, the result of homeostasis between anabolism and catabolism. Types of diabetes: 1- Insulin-dependent diabetes mellitus (IDDM). 2- Non- Insulin-dependent diabetes mellitus (NIDDM). 3- Gestational diabetes. 4- Diabetes insipidus.  Principle Glucose oxidase (GOD) catalyzes the oxidation of glucose to gluconic acid. The formed hydrogen peroxide (H2O2) is detected by a chromogenic oxygen acceptor, phenol, 4-aminophenazone (4-AP) in the presence of peroxidase (POD): GOD D-glucose + O2 + H2O Gluconic acid + H2O2 POD H2O2 + phenol + 4-AP Quinone + H2O The intensity of the color formed is proportional to glucose concentration in the sample. Procedure Assay conditions Wavelength: 546nm (490-550). Cuvette: 1cm light path. Temperature: 37ºC/ 15-25ºC. Adjust the instrument to zero with reagent blank Pipette into a cuvette  Procedure Blank Standard Sample R2 (ml) 1.0 1.0 1.0 Standard µl - 10 - Sample µl - - 10 Mix and incubate for 10 min 37ºC or 30 min at room temperate (15-25ºC). Read the absorbance (A) of the samples and standard, against the blank, the color, is stable for at least 30 minutes.  Calculation Concentration of glucose (mg/ dl) = A Sample\A Standard *100 (standard conc.) Note: mg/dl 0.0555 = mmol/L Expected value Plasma, serum: 60-110 mg/dl ~ 3.33-6.1 mmol/L Clinical significance: Causes of hyperglycemia: (increased blood glucose concentration) 1-Pancreatitis 2- Diabetes mellitus 3- Obesity 4- Acromegaly 5- Hyperthyroidism 6- cushing's syndrome (increase of hepatic gluconeogenesis) 7- Administration of drugs: A-General anesthesia B-morphine C- Thyroid preparation Causes of hypoglycemia Hypoglycemia (decreased blood glucose concentration) Insulinemia Addison's disease Galactosemia Alcohol ingestion Severe liver disease  What is high blood glucose for dental treatment? Maximum acceptable levels of blood glucose for removal of teeth in diabetics are 180 mg/dl (before meal) and 234 mg/dl (2 h after a meal). High blood glucose levels reduce the secretion of nitric oxide (powerful vasodilator) in the body which leads to poor circulation and slow-healing socket.