Determination of Blood (serum) Glucose
Objectives
To understand the importance of measuring
blood glucose level.
To determine the concentration of glucose in
serum sample by a manual method using known
standard.
Blood
Blood is vascular tissue that circulates in the closed
system of blood vessels
Functions:
• Transportation
• Regulation of acid-base balance
• Regulation of body temperature
• Protection against infections
• Coagulation
Blood: Composition
Blood
Plasma
Water
Solids :
Diffusible
- Anabolic
- Catabolic
Nondiffusible
Formed
Elements
RBCs
WBCs
Platelets
Types of Samples
• Plasma
Water + solids (e.g. glucose, urea, albumin, fibrinogen)
No cells
• Serum
Serum = plasma – clotting factors
Plasma vs. Serum
Plasma
Serum
- Anticoagulant
- No anticoagulant
- Contains clotting factors
- Advantage: time saving
- Contains no clotting factors
- Advantage: less interference
Preparation of sample: Serum
Serum
Venous
Blood
Allow blood to clot
(20min.)
Remove the clot
and centrifuge
Transfer the
clear
supernatant
to specimen
tube
cells
Cent. tube
Determination of Blood Glucose
Requirements:
Automatic pipettes
Tips
Cuvettes
 Spectrophotometer
 Reagent
Specimen:
Serum, heparinised or EDTA-plasma
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
Procedure
Blank
Standard
Sample
Determination of Blood Glucose
Procedure (kit)
Reagents
Blank
Standard
Sample
Standard (ml)
-
20
-
Sample (ml)
-
-
20
Biuret reagent (ml)
2
2
2
Procedure
Add the reagents and sample as directed
Mix and let stand at room temperature for 10 min.
Read the absorbance at 505 nm.
Zero the spectrophotometer with the blank reagent.
Read the absorbance's of the standard and samples within 30
min.
Enter the absorbance's readings and calculated the
concentration of the sample.
Calculation
Glugose (mg/dl) = Sample Absorbance
Stand. Absorbance
Normal level
Fasting: 75 -110 mg/dl (3.9 -6 mmol/L)
x Conc of standard
Interpretation of the results
• If BG >110 mg/dl
HYPERGLYCEMIA
• Causes:
1-Diabetis mellitus
3-Acute stress
4-Adrenal hyperactivity (Cushing's syndrome)
5- Hyperthyroidism
6- Pancreatic cancer or pancreatitis
Interpretation of the results: cont.
If BG <70 mg/dl
Causes:
HYPOGLYCEMIA
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)
Glucose Measuring Devices
Used to check Blood Sugar Levels.
Many different types and models.
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Device Variations
Some glucometers turn on automatically.
Know the features of the glucometer your service
uses.
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Cleanse skin with alcohol prep
20
BG Procedure
•The glucometer reading indicates the amount of
glucose in the patient’s blood stream.
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What Now?
Treat the Patient
Document Results
Proper disposal of sharps
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