CARBOHYDRATES&GLUCOSE TESTING Flashcards
are organic compounds composed of
carbon, hydrogen and oxygen
Carbohydrates
Carbohydrates Chemical composition:
Cn(H2O)n
- carbonyl group in the middle linked to 2 other carbon atoms
Ketose
Two forms of CHO
aldose
ketones
- terminal carbonyl group called aldehyde group
Aldose
are the major constituents of physiologic
system: brain, erythrocyte, and retinal cells in humans.They
are also the major source of energy.
Carbohydrates
-simple sugars that cannot be hydrolyzed to a simpler form
- can contain 3 or more carbon atoms
Monosaccharides
types of Monosaccharides
-Glucose
-Fructose
-Galactose
is directly used as energy source and or stored as
glycogen in the liver or muscles.
Glucose
most important CHO; major metabolic fuel
Glucose
two monosaccharides are joined by a glycosidic linkage
Disaccharides
types of Disaccharides
Sucrose
Lactose
Maltose
Fructose + Glucose
Maltose
Glucose + Glucose
Maltose
Galactose + Glucose
Lactose
-linkage of many monosaccharide units
-on hydrolysis, will yield more than 10 monosaccharides
Polysaccharides
types of Polysaccharides
starch
glycogen
chitin
storage form of glucose in the body
Glycogen
fibrous substances consisting of polysaccharides
and forming the major constituent in the exoskeleton of
arthropods and the cell wall of fungi
Chitin
As food enters the mouth and oral cavity, food begins to be
broken down by _____, an enzyme produced by the parotid gland that helps in the initial metabolism of food
ptyalin
When food reaches the stomach, the acidity inactivates ptyalin and acid hydrolysis occurs. There is no carbohydrate digestion in the stomach, but protein digestion happens
through the enzyme _______.
pepsin
When food reaches the intestines, _______, an enzyme produced by the pancreas, further degrades the food and
convert polysaccharides into monosaccharides.
amylopsin
After 2 hours glucose levels go
back to normal
After 30 min glucose levels
rise
After 1 hour glucose levels
peak
What are the Glucose Metabolic Pathway
Embden-Meyerhoff Pathway
Hexose- Monophosphate Shunt
Glycogenesis
a Glucose Metabolic Pathway that can be aerobic and anaerobic
Embden-Meyerhoff Pathway
a pathway that provides energy for the body
Embden-Meyerhoff Pathway
glucose to pyruvate
Aerobic
glucose to lactate
Anaerobic
a pathway for production of reduced
NADPH and ribose-5-phosphate
Hexose- Monophosphate Shunt
glucose to pyruvate or lactate to produce
energy
Glycolysis
– formation of glucose-6-phosphate from
non-carbohydrate sources
Gluconeogenesis
– breakdown of glycogen to glucose for
energy
Glycogenolysis
– glucose to glycogen for storage
Glycogenesis
– conversion of carbohydrates to fatty acids
Lipogenesis
– Decomposition of fat
Lipolysis
- produced by the β cells of the islets of Langerhans in the
pancreas - only hormone that decreases glucose
- promotes glycolysis, glycogenesis, lipogenesis
Insulin
- produced by the α cells of the islets of Langerhans in the
pancreas - primary hormone that decreases glucose for increasing
glucose levels - promotes glycogenolysis and gluconeogenesis
Glucagon
immediate precursor of insulin
proinsulin
test that is based on the presence of proinsulin
that helps in the differential diagnosis of Type 1 from type 2
Diabetes Mellitus and the diagnosis of insulinomas
c peptide
- produced by the δ cells of the islets of Langerhans in the
pancreas - inhibition of pancreatic hormone release of insulin and
glucagon - inhibition of gastric acid secretion
Somatostatin
- produced by the zona fasciculata of the adrenal cortex
- promotes hepatic gluconeogenesis and lipolysis
Cortisol
- produced by the chromaffin cells of the adrenal medulla
- inhibits insulin secretion and promotes glycogenolysis
Catecholamines
- produced by the anterior pituitary gland
- promotes glycogenolysis and gluconeogenesis
Adenocorticotropic Hormone
- produced by the anterior pituitary gland
- promotes glycogenolysis and lipolysis
Growth Hormone
- produced by the thyroid gland
- promotes glycogenolysis and intestinal absorption of
glucose
Thyroid hormones
- low blood glucose levels
-May be due to insulinoma or diabetic shock
Hypoglycemia
value when glucagon and other glycemic factors start to
increase
65-70 mg/dL
value observable symptoms; strongly suggest hypoglycemia
55 mg/dL
panic value
<40 mg/dL
value for severe CNS dysfunction
20-30 mg/dL
high blood glucose levels
(FBS >126mg/dL)
Hyperglycemia
Values greater than _____ may result to multiple organ
failure (nephropathy, neuropathy, retinopathy)
500 mg/dL
- Symptoms present
- Low blood glucose
- Relief of symptoms when glucose is raised to normal
Whipple’s Triad
is the most common type of hyperglycemia that can either be due to insufficient/complete
absence level of insulin or insulin resistance
Diabetes Mellitus
Diabetes MellitusClinical signs and symptoms include
Polyuria
Polydipsia
Polyphagia
- excessive thirst
Polydipsia
- excessive urination
Polyuria
is the presence of glucose in the urine
Glucosuria
- increased food intake
Polyphagia
is the slight increase of albumin in the
urine that is due to the kidneys leaking out small amounts of
albumin passed through the urine
Microalbuminuria
DM Non-diabetic___ mg/dL
< 100
DM Pre-diabetes ______mg/dL
100-125
DM RBS = _____mg/dL
≥ 200
DM OGTT =_____mg/dL
≥ 200
DM HbA1c ____
≥ 6.5%
-also known as Insulin dependent DM, Brittle diabetes,
Juvenile onset DM
-caused by the cellular-mediated autoimmune destruction of
the beta cells of the islets of Langerhans in the pancreas
Type I Diabetes Mellitus
-signs and symptoms: Weight gain, milder symptoms than
Type I DM
-Not prone to ketoacidosis
-C-peptide: detectable/high
-Management: Healthy lifestyle
Type II Diabetes Mellitus
- signs and symptoms: Rapid weight loss, hyperventilation,
mental confusion, possible loss of consciousness
-Prone to ketoacidosis
-C-peptide: Undetectable to very low
-Treatment or management include Exogenous Insulin
Therapy
Type I Diabetes Mellitus
-also known as Non-insulin dependent DM, Stable
diabetes, Adult onset DM
- caused by insulin receptor defect leading to insulin resistance
Type II Diabetes Mellitus
-pregnancy onset usually in the second trimester due to
hormonal imbalance
-Occurs during pregnancy and should disappear after delivery
- May lead to Type 2 DM after 5-10 years if not treated
Gestational Diabetes Mellitus
Infants born to diabetic mothers are at increased risk for
respiratory distress syndrome, hypocalcemia, and
hyperbiliruninemia
Gestational Diabetes Mellitus
Screening should be performed between ___
weeks of gestation (1-hr Glucose Challenge Test using 50g
glucose load)
24th and 28th
can be used as specimens for glucose testing
Whole blood, serum, plasma, CSF, urine, synovial fluid
Glucose is metabolized at a rate of:
7 mg/dL /hr at Room Temp 2 mg/dL /hr at 4°C
Whole blood glucose levels are lower than serum
blood glucose levels
10-15%
- screening test for DM
- detect elevation of blood glucose
- 8-10 hours fasting is required; not more than 16hrs
- produced by the β cells of the islets of Langerhans in the
pancreas
Fasting Blood Sugar (FBS)
Categories of fasting plasma glucose
- Normal = ____ mg/dL
- Impaired fasting glucose = ______ mg/dL
- Provisional Diabetes dx = _____mg/dL
<110
>110- <126
>126
- sugar determination of randomly collected blood
- requested during insulin shock or hyperglycemic ketonic
coma
Random Blood Sugar (RBS)
- FBS is first performed
- Patient is then given a glucose load (75g)
- plasma glucose is determined after 2hrs
- NORMAL: blood glucose will return within reference limits
after 2 hours
2-hr Postprandial Blood Sugar
- series of glucose testing
- FBS is first performed
- Patient is then given a glucose load
- collect blood specimen after 30 min, 1 hr and 2 hrs after
glucose load intake
Oral Glucose Tolerance Test (OGTT)
- detects impaired glycogenolysis or severe liver damage
Galactose Tolerate Test
- for those who cannot take large carbohyrate intake, altered
gastric physiology, undergone operation in intestine,
chronic malabsorption syndrome
Intravenous Tolerance Test (IVTT)
glucose load: ___ for adult; _____ for pregnant; ____for children
75g, 100g, 1.75g/kg wt
- evaluates sensitivity to insulin
- glucose is administered orally 30min after insulin
Insulin Tolerance Test (ITT)
- used for children suffering from hypoglycemic episodes
Leucine Tolerance Test
FBS is measured before giving the glucose load
*if FBS ____ mg/dL = stop test; if ____ mg/dL, proceed
> 140, < 140
- Hba1c is formed by attachment of glucose to the beta
chains of Hemoglobin A1 - Long term monitoring of glucose
- Detects glucose levels in the average of 2-3 months since
the RBC lifespan in the circulation is 120 days - Not suitable for patients with RBC lifespan disorders
Glycosylated haemoglobin (HbA1c)
- to evaluate the hypoglycemic effects by insulinomas
Tolbutamide Tolerance Test
Glycosylated haemoglobin (HbA1c) Specimen: ______
- Normal value: ____
- (______ =prediabetes)
Whole blood EDTA
< 6.5%
5.7-6.4%
- is formed by attachment of glucose to
albumin - Short term monitoring of glucose
- Detects glucose levels in the average of 2-3 weeks since
the lifespan of albumin in the circulation is 20 days - Not suitable for patients with hypoalbuminemia
Fructosamine
(oldest method)
- Principle: glucose in a hot alkaline solution readily reduces cupric ions to cuprous ions
Copper Reduction Methods
Fructosamine Normal value: ____
205-285 µmol/L
Fructosamine specimen:
Serum
Cuprous + phosphomolybdate = phosphomolybdenum blue
- Disadv: non-glucose reducing sugars are not precipitated
during process
Folin Wu Method
Cuprous+arsenomolybdate = arsenomolybdenum blue
- Adv: non-glucose reducing sugars are adsorbed by barium
sulfate
Nelson Somogyi Method
Cuprous + Neocuproine reagent = yellow-orange complex
Neocuproine Method
Cuprous + Iodine + Acidic solution = colorless complex
- excess iodine is titrated with thiosulfate
Shaffer-Hartman Somogyi Method
Copper sulfate (blue) + glucose + heat = brick red
precipitate
Benedict’s Method (modified Folin Wu method)
Ferricyanide (yellow) + glucose = ferrocyanide (colorless)
- inverse colorimetry; measured at 420 nm
Hagedorn-Jensen Method
defect in glycogen metabolism
GLYCOGENOSES
glucose + 0-toluidine + acetic acid + heat = green complex
(630 nm)
- most specific non-enzymatic method for glucose
Dubowski Method (o-Toluidine Method)
defect Glucose-6-phosphatase
Von Gierke disease
defect in Glycogen debranching
enzyme
Anderson’s disease
defect Lysosomal acid α-glucosidase
Pompe disease
defect in Muscle phosphorylase
McArdle disease
defect in Glycogen phosphorylase
(liver)
Hers disease
defect in Phosphofructokinase
Tarui disease
defect in GLUT 2
Fanconi-Bickel
disease