Chemical and Enzymatic Methods Flashcards
Chemical Methods include:
- ALKALINE COPPER REDUCTION METHOD
- ALKALINE FERRIC REDUCTION METHOD / HAGEDORN JENSEN
- CONDENSATION METHOD
ALKALINE COPPER REDUCTION METHOD includes:
FOLIN WU
NELSON SOMOGYI
NEOCUPROINE
BENEDICT’S
Reduce cupric ion to cuprous ion by the action of a reducing substance such as glucose
ALKALINE COPPER REDUCTION METHOD
Cu2+ + phosphomolybdic acid → phosphomolybdenum (blue)
FOLIN WU
Cu2+ + arsenomolybdic acid → phosphomolybdenum (blue)
NELSON SOMOGYI
Cu2+ + neocuproine → Cu – neocuproine (yellow/ y-orange)
NEOCUPROINE
end color of neocuproine
(yellow/ y-orange)
contains Cu(OH)2 copper hydroxide
Benedict’s reagent
end color of benedict’s
brick red precipitate
ALKALINE FERRIC REDUCTION METHOD aka
hagedorn jensen
ALKALINE FERRIC REDUCTION METHOD is _ method and _
TITRIMETRIC METHOD and INVERSE COLORIMETRY
Initial is colored and the final reaction is colorless.
Reduction of color is measured
INVERSE COLORIMETRY
in hagedorn jensen,
Potassium ferricyanide (yellow) is reduced when heated in an alkaline solution by a reducing sugar such as glcose, produces _ (colorless)
Potassium ferrocyanide
Uses: Ortho-toluidine is an aromatic amine
CONDENSATION METHOD
Method that uses glucose with aromatic amine forms schiff’s base when heated in an acidic sol’n
Absorbance:
Interferences:
Condensation Method
Absorbance: 630nm
Interferences: galactose & mannose can also form schiff’s base
Condensation Method’s acidic soln
glacial acetic
ENZYMATIC METHODS include:
- GLUCOSE OXIDASE METHOD
- HEXOKINASE METHOD
- GLYCOSYLATED HEMOGLOBIN METHODS
The most specific enzyme reacting with only B-D-Glucose
GLUCOSE OXIDASE METHOD
more abundant D-glucose in the blood
b-glucose (64%)
a-glucose in the blood
34%
Total Glucose also measures the a-glucose by adding the enzyme_ that will convert a-glucose to b-glucose.
Mutarotase
GLUCOSE OXIDASE METHOD falsely increase in
bleach
GLUCOSE OXIDASE METHOD falsely decrease in
ascorbic acid, uric acid, bilirubin, hemoglobin, tetracycline,
glutathione
GLUCOSE OXIDASE METHOD two methods:
COUPLED ENZYMATIC REACTION / SAIFER GERNSTENFIELD METHOD
POLAROGRPAHIC METHOD
enzyme used in coupled enzymatic method
glucose oxidase and peroxidase
uses enzyme and end product has color which is measured using a spectrophotometer
Enzymatic-Colormtetric Method
reduced chromogens in coupled enzymatic rx
3-methyl-2 benzothiazolinone hydrazone
N,N-dimethylaniline
O-dianisidine
glucose oxidase method principle
Trinder Rx
Measurement of the degree of oxygen consumption using a pO2 (Clark) electrode
POLAROGRPAHIC METHOD
POLAROGRPAHIC METHOD
- Do not use _ sample as cells consume oxygen and may cause _
whole blood; FI
POLAROGRPAHIC METHOD
requires addition of
molybdate and iodide or
catalase and ethanol
Reference method for glucose determination because it uses an enzyme that is more accurate than Glucose Oxidase
HEXOKINASE METHOD
hexokinase method enzyme :
hexokinase and G-6-PD
enzyme that presence will not affect the glucose concentration
hexokinase
enzyme not affected by ascorbic acid and uric acid
g-6-pd
hexokinase method
samples:
interferences:
samples: Serum, Plasma, CSF, Urine, Serous fluid
interferences: Hemoglobin, Drugs, Bilirubin, Lipemia
GLYCOSYLATED HEMOGLOBIN specimen
EDTA whole blood (does not require fasting)
GLYCOSYLATED HEMOGLOBIN METHOD
preferred method of choice as it
is not affected by HbF, HbS, and HbC
AFFINITY CHROMATOGRAPHY
GLYCOSYLATED HEMOGLOBIN METHOD
temperature-dependent.
HbF can cause FI.
HbS and HbC causes FD.
CATION-EXCHANGE CHROMATOGRAPHY
all forms of Hgb are measured and quantitated. A separation technique.
HIGH PERFORMANCE LIQUID CHROMATOGRAPHY
1st reagent in GLYCOSYLATED HEMOGLOBIN METHODS
lysing agent
GLYCOSYLATED HEMOGLOBIN METHODS
AFFINITY CHROMATOGRAPHY
CATION-EXCHANGE CHROMATOGRAPHY
HIGH PERFORMANCE LIQUID CHROMATOGRAPHY
ELECTROPHORESIS
LATEX IMMUNOAGGLUTINATION INHIBITION METHODOLOGY
Recommended Frequency for DM Patients (ADA Guidelines)
o DM patients with stable glycemic control:
twice a year (every 6months)
Recommended Frequency for DM Patients (ADA Guidelines)
o DM patients with unstable glycemic control:
quarterly (every 3 months)
Most common method (uses glucometer and reagent strips)
— useful for monitoring hyperglycemia and hypoglycemia among diabetic patient
self-monitoring of glucose
WHOLE BLOOD GLUCOSE
tests which can be done outside the laboratory
POCT (POINT OF CARE TESTING)
How often do we measure whole blood glucose for diabetic px in Type 1 DM
3-4x /day
specimen for self-monitoring glucose
capillary blood
