Lec 13: Glucose Methodologies

Question 1

1. Normal CSF levels
2. Approximate CSF Glucose concentrations in the blood.
3. How much time is required to restore CSF blood glucose equilibrium?

Answer 1

1. 40–70 mg/dL
2. 60–75%
3. 2 hours

Question 2

Screening processes should be able to detect urine glucose levels of ____ mg/dL.

Answer 2

More than 30 mg/dL

Question 3

What are the 4 factors considered to achieve accuracy and reliability?

Answer 3

1. Choice of sample
2. Choice of method
3. Issues related to specificity
4. Ease of measurement

Question 4

CHOICE OF SAMPLE

Why are the cells separated from the liquid portion of blood within 1 hour?

Answer 4

RBCs have enzymes that would metabolize glucose

Question 5

Fasting Blood glucose should be obtained in the ___ after approximately ___ hours of fasting.

Answer 5

Morning, 8 to 10 hours

Question 6

CHOICE OF SAMPLE

When collecting plasma sample, what anticoagulant/preservative is used?

Answer 6

Sodium fluoride (Gray top)

Question 7

What are the choices of method?

Answer 7

• Spectrophotometric assay
• Enzymatic method
- glucose oxidase
- hexokinase

Question 8

CONVERSION FACTOR
glucose mg% —> glucose mmol/L

Answer 8

0.055

Question 9

These prevent most glucose consumption by the erythrocytes or leukocytes.

Answer 9

Fluoride, Iodoacetate

Question 10

When measuring glucose, the method used is based on its _____ property.

A. Oxidation
B. Reduction

Answer 10

B. Reduction

Question 11

Alkaline Copper Reduction Method: FOLIN WU

1. Source of cupric ion
2. Color reagent
3. End product

Answer 11

1. Alkaline Copper Tartrate
2. Phosphomolybdic acid
3. Phosphomolybdenum blue

Question 12

Alkaline Copper Reduction Method: NELSON-SOMOGYI

1. Acts as an adsorbent to which saccharoids adhere.
2. Color reagent.
3. End product.

Answer 12

1. Barium Sulfate
2. Arsenomolybdate
3. Arsenomolybdenum blue

Question 13

The 5 specific methods under Alkaline Copper Reduction Method

Answer 13

1. Folin Wu method
2. Nelson-Somogyi method
3. Neocuproine method (Bitter & Manning)
4. Benedict’s method
   
   • modification of Folin Wu
   • uses Bisulfate Copper solution
5. Shaeffer-Hartmann Somogyi

Question 14

A specific method under Alkaline Ferric Reduction Method.

Answer 14

Hagedorn Jensen Method

Question 15

CONDENSATION METHODS

Enumerate the methods along with their specific methods and describe.

Answer 15

Condensation with Aromatic Amines
1. O-toluidine method (gluconeer)
• Glucose in PFF reacts with 1° aromatic amines in a hot GAA
• end product: green color
• 630 nm

Condensation with Phenols
1. Condensation with Anthrone

Question 16

GLUCOSE OXIDASE METHODS: Saifer Gerstenfeld

1. End Product (color) of the oxidized chromogen.
2. Name of the oxidized chromogen.

Answer 16

1. Blue
2. 3-methyl-2 benzothiazolinone hydrazone / N,N-dimethylanaline

Question 17

Enumerate the Glucose Oxidase Methods

Answer 17

• Saifer Gerstenfeld
• Polarographic
• Dextrostix

Question 18

GLUCOSE OXIDASE METHODS: Polarographic

1. Principle
2. H2O2 + Iodide. [Give the enzyme & end product]
3. H2O2 + ethanol [Give the enzyme & end product]

Answer 18

1. Amount of oxygen consumed in the oxidation of glucose to gluconic acid is measured using a polarographic oxygen electrode
2. Molybdate (enzyme), Iodine (end)
3. Catalase (enzyme), water & acetaldehyde (end)