[2S] UNIT 6 Carbohydrates Flashcards
Major food source and energy supply for the body
Carbohydrates
Where is carbohydrates stored as glycogen?
Liver & Muscle
Found in connective tissues and nucleic acids
Carbohydrates
FBS: increased in plasma glucose level seen in diabetic patient
Hyperglycemia
Produces ATP for active movement of substances
Carbohydrates
Increase level of glucose
Hyperglycemia
T/F: Hyperglycemia can be caused by factors like pancreatectomy, hemochromatosis and stress
T
T/F: Hyperglycemia can be caused by factors like mild infection, dehydration, pregnancy, and abnormal insulin receptor
F; severe infection
Decreased plasma glucose level
Hypoglycemia
Seen in diabetic patient who injects insulin
Hyperglycemia
T/F: Diabetic patient who injects insulin have 1 or 2 episodes of symptomatic hypoglycemia per week
T
Produced by B-cells of pancreatic islets of Langerhans
Insulin
Hormone that decreases plasma glucose levels
Insulin
Primary hormone responsible for the entry of glucose into the cell.
Insulin
Primary hypoglycemic agent
Insulin
Regulates glucose by increasing glycogenesis, lipogenesis, and glycolysis and inhibiting glycogenolysis
Insulin
Formation of glycogen from glucose
Glycogenesis
Process of fatty acid and triglyceride synthesis from glucose or other substrates
Lipogenesis
Breakdown of glucose in the formation of lactate, pyruvate, or other intermediate products such as ATP
Glycolysis
Breakdown of glycogen into glucose
Glycogenolysis
Primary hormone responsible for increasing glucose levels
Glucagon
Increases plasma glucose levels by glycogenolysis
and gluconeogenesis
Glucagon
Secreted by α-cells of pancreatic islets of Langerhans
Glucagon
Measured routinely using serum or plasma
○ Whole blood
○ Urine
○ CSF
○ Other body fluids
Glucose
Formation of glucose from non-carbohydrate sources like amino acid, lactic, acid, glycerol, fats, and protein
Gluconeogenesis
T/F: In Glucagon, glucose is metabolized for the uptake of cells to other parts of the body
F; glycogen
Approximately 7 mg/dL lower than capillary blood due to tissue metabolism
Venous blood glucose
Approximately 11% lower than serum or plasma glucose
Whole blood glucose
T/F: Glycolysis lowers the glucose levels in an uncentrifuged blood specimen
T
Approximately 60-70% plasma glucose levels
CSF glucose levels
Obtained in the morning (8-10 hrs fasting, not longer
than 16 hrs)
Fasting Blood Glucose
Can inhibit in vitro glycolysis
Sodium Fluoride Tube (Gray)
T/F: Fasting Plasma Glucose has diurnal variation: ↑ AM than in PM
T
METHODS OF GLUCOSE DETERMINATION
Alkaline copper reduction method
Non-Enzymatic
Sodium Fluoride Tube (Gray) is stable for up to _ days at room temp
3
METHODS OF GLUCOSE DETERMINATION
Condensation method
Non-Enzymatic
METHODS OF GLUCOSE DETERMINATION
Alkaline ferric reduction method
Non-Enzymatic
METHODS OF GLUCOSE DETERMINATION
Glucose oxidase
Enzymatic
METHODS OF GLUCOSE DETERMINATION
Hexokinase
Enzymatic
Principle: Reduction of cupric ions to cuprous ions forming cuprous oxide in hot alkaline solution by glucose
○ Redox reaction
Alkaline Copper Reduction Method
Glucose + alk. cupric tartrate → CuOH + heat → cuprous
oxide
ACR: Nelson Somogyi Method & Folin Wu
METHODS OF GLUCOSE DETERMINATION
Glucose dehydrogenase
Enzymatic
Most commonly used chemical method
ACR: Nelson Somogyi Method
Cu2O + arsenomolybdic acid → arsenomolybdenum
blue
ACR: Nelson Somogyi Method
○ Add Barium sulfate (BaSO4) when preparing
Protein-Free Filtrates to remove saccharoids
(non-glucose reducing substances)
○ Measures true blood glucose
ACR: Nelson Somogyi Method
Glucose + alk. cupric tartrate → CuOH + heat → cuprous oxide
ACR: Folin Wu Method & Nelson Somogyi Method
Cu2O + phosphomolybdic acid → phosphomolybdenum blue
ACR: Folin Wu Method
Glucose + alk. cupric-neocuproine → Cuprous-neocuproine complex
ACR: Neocuproine Method
Glucose + CuSO4 (blue) + heat → Cu2O
ACR: Benedict’s Method
2,9-dimethyl-1,10-phenanthroline-8-cl
ACR: Neocuproine Reagent Formula
End color: yellow to yellow-orange
ACR: Neocuproine Method
Uses tartrate & citrate as stabilizing agent
ACR: Benedict’s Method
End color: green → yellow → orange → brick red
ACR: Benedict’s Method
Principle: Reduction of ferricyanide to ferrocyanide in hot alkaline solution by glucose
Alkaline Ferric Reduction Method
Glucose + [Fe(CN)6]
3 − (yellow) in alk soln + heat → [Fe(CN)6]4− (colorless)
AFR: Hagedorn Jensen Method
End color: bluish green
Ortho-Toluidine Method
Inverse colorimetry
AFR: Hagedorn Jensen Method
Glucose + o-toluidine + acetic acid + heat → N-glucosylamine
Ortho-Toluidine Method
Principle: Ability of primary aromatic amine acid
solution to condense with the aldehyde group of
glucose to form glycosylamines (Schiff bases)
Condensation Method
Main interfering substances in condensation method
○ Galactose (aldohexose)
○ Manose (aldopentose)
● Also called Saifer Gernstenfield method
● One of the most used in blood glucose determination
● Prone to errors
Glucose Oxidase Method
● Step 1: Mutarotase catalyzes mutarotation of α- to β-glucose
● Step 2 & 3: Trinder reaction – couple reaction
Glucose Oxidase Method
Considered as the reference method for blood
glucose determination
Hexokinase Method
tetrazolium bromide salt (colorless)
MTT (glucose dehydrogenase)
Increased or Decreased Carbo?
Diabetes Mellitus
Increased
Increased or Decreased Carbo?
Pancreatitis
Increased
Increased or Decreased Carbo?
Pituitary or thyroid dysfunction
Increased
Increased or Decreased Carbo?
Renal failure
Increased
Increased or Decreased Carbo?
Insulin-induced hypoglycemia
Decreased
Increased or Decreased Carbo?
Liver disease
Increased
Increased or Decreased Carbo?
Starvation
Decreased
Increased or Decreased Carbo?
Hyperinsulinemia
Decreased
Increased or Decreased Carbo?
Neoplasms
Decreased
Conversion factor of mg/dL to mmol/L
0.0556
Conversion factor of mmol/L to mg/dL
18
Tubes used in Glucose Oxidase Method
Kahn Tubes
Enzyme reagents of the glucose reagent kit
4 PP ni GPS
4-aminoantipyrine
Phosphate buffer (pH 7.4)
Phenol
Glucose oxidase
Peroxidase
Sodium azide
What to pipet first?
a. Blank
b. Standard
c. Normal Control
d. Pathologic Control
e. Unknown
b. Standard
GLUCOSE OXIDASE METHOD
Where to pipet when purging the standard?
Deliver it into the tube by touching the tip of the pipet directly to the bottom of the tube
GLUCOSE OXIDASE METHOD
How to pipet the reagent in the tube?
By touching the tip of the pipet to the side of the tube
GLUCOSE OXIDASE METHOD
PROCEDURE 7: Mix the solution by covering the mouth of the test tube with a ________ and inverting the tubes _____.
parafilm
2-3x
GLUCOSE OXIDASE METHOD
PROCEDURE 8: Incubate for ______ at _____ water bath.
5 minutes at 37°C
GLUCOSE OXIDASE METHOD: ASSAY REQUIREMENTS
Wavelength
500 nm
GLUCOSE OXIDASE METHOD: ASSAY REQUIREMENTS
Optical Path
1 cm
GLUCOSE OXIDASE METHOD: ASSAY REQUIREMENTS
Temperature
37°C
GLUCOSE OXIDASE METHOD: ASSAY REQUIREMENTS
Measurement
Read against reagent blank
GLUCOSE OXIDASE METHOD
PROCEDURE 10: Measure absorbance of all tubes within ___ minutes
60 minutes
Reference Value of Glucose
CU = 70-110 mg/dL
SI = 3.9 - 6.1 mmol/L