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Saturday, April 11, 2009

Blood Glucose Determination

Glucose levels are maintained in the body at 60-100 mg/dL and this is done through the body's homeostatic ability.

When the glucose levels increase, the primary hormone that decreases the level is insulin. On the other hand, the primary hormone that increases glucose levels when it is below normal, is glucagon.

Both of these hormones are produced by the pancreas in the beta and alpha cells of the Islets of Langerhans, respectively.

Since blood glucose levels are affected by diet through the food that we eat, fasting is required before a test is performed ( except in cases of RBS - Random Blood Sugar).

In the colorimetric method of glucose determination, The Orthotoluidine Method is the most common method utilized.

MANUAL PROCEDURE:

Precautions:

1. Patient should have fasted for 8-12 hours.
2. Unhemoylzed, non icteric and non turbid serum should be used to avoid interferences with the procedure.
3. The reagent contains sodium azide, which is corrosive, so PPE should be worn.
4. The solution should be brought to a boil to ensure proper reaction

MANUAL PROCEDURE:

Precautions:

1. Patient should have fasted for 8-12 hours.
2. Unhemoylzed, non icteric and non turbid serum should be used to avoid interferences
with the procedure.
3. The reagent contains sodium azide, which is corrosive, so PPE should be worn.
4. The solution should be brought to a boil to ensure proper reaction.

PROCEDURE PROPER:

1. Prepare Three tubes labeled, SA (Sample)/ C (Control), ST (Standard) and RB (Reagent Blank).

2. To the SA/C tube add 0.1 ml of the test specimen/ Control specimen.

3. To the ST tube add 0.1 ml of the standard stock solution.

4. To the RB tube add 0.1 ml of distilled water.

5. Add 4 ml of glucose reagent to all tubes. Cap and mix by gentle inversion.

6. Boil all tubes at 100 degrees centigrade for 8 minutes.

7. Cool tubes in running tap water for about 2 minutes.

8. Read absorbance of solutions in the spectrophotometer with appropriate cuvets at 636 nanometers against the RB (Reagent Blank).

9. Compute for the Cu (Concentration of the Unknown making use of the formula:

Cu= Absorbance of Unknown(Au) multiplied by the Concentration of the
Standard(Cs) divided by the Absorbance of the Standard (As)

Adapt the unit of the Cs

Normal Values = 60 - 100 mg/dL
to convert values to mmol/L multiply values in mg/dL with 0.0555

The clinical significance of the elevation of blood glucose denotes an abnormality in the body. One of the main causes of elevated blood levels is diabetes mellitus. It maybe Type 1, Type 2.

Further testing maybe done using OGTT (Oral Glucose Tolerance Test) or 2HPPT (2 Hour Post Prandial test). The 2HPPT is more sensitive as a test for diagnosis of DM (diabetes mellitus). There are two types of DM: Type 1 and Type 2.