measuring urine glucose concentration

• The presence of glucose in urine is an indicator that a person may have diabetes
• If blood glucose concentration increases above the renal threshold

  Not all the glucose from the filtrate in the proximal convoluted tubule is reabsorbed and some will be left in the urine
• Test strips


  Can be used to test urine for the presence and concentration of glucose
• Enzymes immobilized on a test strip

  • Glucose oxidase
  • Peroxidase
• Testing urine with test strips

  1. Immersing pad in urine sample

  2. Glucose oxidase catalyses reaction

  3. Peroxidase catalyzes reaction

  4. Comparing pad colour to chart
• Glucose oxidase

  Catalyses a reaction in which glucose is oxidized to form gluconic acid and hydrogen peroxide
• Peroxidase

  Catalyzes a reaction between hydrogen peroxide and a colorless chemical in the pad to form a brown compound and water
• The colour of the pad is compared to a colour chart, different colours represent different concentrations of glucose
• The higher the concentration of glucose

  The darker the colour
• Urine tests only show whether the blood glucose concentration was above the renal threshold while urine was collecting in the bladder
• Urine tests do not indicate the current blood glucose concentration