glucose, quantitative determination. hormonal regulation of blood glucose
TRANSCRIPT
Glucose, quantitative determination
Hormonal regulation of blood glucose
Methods
• Chemical
• Enzymatic
CHEMICAL METHODS
• Oxidation - Reduction Methods – Folin – Wu– Somogyi - Nelson
• Condansation Methods– Orto - Toluidine
Benedict reaction
Folin - Wu
Glucose + CuGlucose + Cu2+2+ >>>Gloconate + >>>Gloconate + CuCu++
pH > 7 , heatpH > 7 , heat
CuCu++ + phosphomolybdate + phosphomolybdate
Blue molybdenium complexBlue molybdenium complex λλ = 660 nm = 660 nm
Somogyi - Nelson
Glucose + CuGlucose + Cu2+2+ >>> >>> Gloconate + CuGloconate + Cu++
pH > 7 , heatpH > 7 , heat
CuCu++ + arsenomolybdate >>> + arsenomolybdate >>> blue molybdenium complex blue molybdenium complex
λλ = 660 nm = 660 nm
O - Toluidine Method
o - Toluidineo - Toluidine + Glucose + Glucose >>> >>> GlycosylamineGlycosylamine
pH < 7 , heatpH < 7 , heat
Schiff BaseSchiff Base
λλ = 630 nm color complex = 630 nm color complex
CH3
NH2
Interference
• Bilirobin• Galactose• Mannose• Hemoglobin
Enzymatic Methods
• Glucose Oxidase
• Hexokinase
• Glucose dehydrogenase
Glucose Oxidaseαα -D-Glucose -D-Glucose ββ-D-Glucose-D-Glucose
OO22 glucose oxidaseglucose oxidase
Gluconic acid + Gluconic acid + HH22OO22 PeroxidasePeroxidase
HH22OO22 + chromogen + chromogen Color complexColor complex (o-dianisidine)(o-dianisidine) + H + H22O O (phenylamine)(phenylamine) λλ = 520 nm = 520 nm
Mutarotase
• Glucose oxidase Inhibited by– High concentrations of uric acid, ascorbic acid,
bilirubin, glutathione, creatinine. L-cysteine, L-dopa. Dopamine, methyldopa and citric acid
Hexokinase method
Glucose dehydrogenase method
Clinical Significance
• F.B.S (Fasting Blood Suger)• Fasting 12 - 14 hours• Normal Range 70 - 110 mg/dL• Decrease
– Hypoglycemia
• Increase – Hyperglycemia
Criteria for the diagnosis of diabetes mellitus
Diagnosis of Pre-Diabetes and Diabetes Mellitus
Hyperglycemia
• FBS > 140 mg/dL• Primary (Diabetes Mellitus)
– IDDM (type I)– NIDDM (type II)
• Absolute deficiency of insulin– Make up about 10% of all patients with D.M.
• IDDM persent at an early age (usually before 30)
• Clinical signs :– Blood glucose– Insulin (decreased)– Ketosis – Loss of body weight
Insulin Dependent Diabetes Mellitus (IDDM)
Noninsulin Dependent Diabetes Mellitus (NIDDM)
• Deficiency of insulin receptorDeficiency of insulin receptor• Patients are commonly obesePatients are commonly obese• NIDDM is the most common from of D.M. ( 80-NIDDM is the most common from of D.M. ( 80-
90%)90%)• Usually first present at an age over 40Usually first present at an age over 40• Clinical signsClinical signs
– Blood glucose– Insulin– Osmotic diuresis – Dehydration
Characteristics of Type 1 and Type 2 Diabetes
Response of plasma insulin to glucose stimulation
Secondary hyperglycemia
• Pancratectomy
• Acromegaly
• Cushing’s syndrome
• Glucagonoma
Hypoglycemia
• Adult < 45 - 50 mg/dL in fasting
• Infant – Preterm < 25 mg/dL– Fullterm < 35 mg/dL
Causes of hypoglycemia
• Insulinoma (islet cell tumors)• Glycogen Storage Diseases (GSD)• Addison’s disease
OGTT
Fasting 80 mg/dL0.5 155 mg/dL1 165 mg/dL2 140 mg/dL3 80 mg/dL
Oral Glucose Tolerance Tests (OGTT)
Screening and diagnosis of gestational diabetes mellitus
OGTT curve
2hpp
• 2hpp (two hours postprandial plasma glucose) – To screen for diabetes mellitus – To monitor glucose control
Glycated hemoglubin
• HbA1c
• an index of average blood glucose levels over the past 2-4 months.
• People without diabetes have HbA1c levels between 4-6%.
• Measure HbA1C levels every 3-6 months to monitor glycemic control
Blank Standard Test
Water 0.05 ml - -
Standard 100 mg/dL
- 0.05 ml -
Test - - 0.05 ml
Reagent 3 ml 3 ml 3 ml
• Put 10 minute in boil water bath
• read at 630 nm
• Ct = At / Ast * Cst