BIOCHEMISTRY Blood Glucose

Determination of Blood Glucose (BG) BG is determined by 2 methods: 1- Oxidation method ( enzymatic method): Principle -Glucose +O2 + H2O Glucose oxidase Gluconic acid + H2O2 -H2O2 + phenol + amino-4-antipyrine Peroxidase Quinoneimine +H2O

Determination of Blood Glucose: Oxidation Method Procedure Sample name Stand. name Serum 0.1 ml 0.1 ml Stand. 1 ml 1 ml Reagent Mix , then incubate at 37°C for 10 min. Read the absorbance of sample & stand. at λ= 505 nm against blank (reagent)

Calculation Glugose (mg/dl) = Sample absorbance x conc of standard Stand. Absorbance Normal level Fasting: 75 -110 mg/dl (3.9 -6 mmol/L)

Interpretation of the results If BG >110 mg/dl HYPERGLYCEMIA Causes: 1-Diabetis mellitus 2-Acromegaly 3-Acute stress 4-Adrenal hyperactivity (Cushing's syndrome) 5- Hyperthyroidism 6- Pancreatic cancer or pancreatitis 7- Drugs: e.g. corticosteroids

Interpretation of the results: cont. If BG <70 mg/dl HYPOGLYCEMIA Causes: 1- Insulin overdose 2- Hypothyroidism & hypopituitarism 3- Adrenal insufficiency (Addison's disease) 4- Liver diseases 5- Starvation

Renal glucose threshold Definition: -The blood glucose concentration at which the kidneys start to excrete glucose into the urine -BG level of 180 mg/dl is called Renal Glucose Threshold Glucoseurea Appearance of glucose in urine (occurs when BG conc. > 180 mg/dl)

Renal glucose threshold