CARBOHYDRATES&GLUCOSE TESTING Flashcards by LYNMIL MORENO

are organic compounds composed of
carbon, hydrogen and oxygen

Carbohydrates

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Carbohydrates Chemical composition:

Cn(H2O)n

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carbonyl group in the middle linked to 2 other carbon atoms

Ketose

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Two forms of CHO

aldose
ketones

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terminal carbonyl group called aldehyde group

Aldose

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are the major constituents of physiologic
system: brain, erythrocyte, and retinal cells in humans.They
are also the major source of energy.

Carbohydrates

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-simple sugars that cannot be hydrolyzed to a simpler form
- can contain 3 or more carbon atoms

Monosaccharides

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types of Monosaccharides

-Glucose
-Fructose
-Galactose

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is directly used as energy source and or stored as
glycogen in the liver or muscles.

Glucose

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most important CHO; major metabolic fuel

Glucose

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two monosaccharides are joined by a glycosidic linkage

Disaccharides

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types of Disaccharides

Sucrose
Lactose
Maltose

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Fructose + Glucose

Maltose

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Glucose + Glucose

Maltose

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Galactose + Glucose

Lactose

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-linkage of many monosaccharide units

-on hydrolysis, will yield more than 10 monosaccharides

Polysaccharides

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types of Polysaccharides

starch
glycogen
chitin

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storage form of glucose in the body

Glycogen

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fibrous substances consisting of polysaccharides
and forming the major constituent in the exoskeleton of
arthropods and the cell wall of fungi

Chitin

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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

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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

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When food reaches the intestines, _______, an enzyme produced by the pancreas, further degrades the food and
convert polysaccharides into monosaccharides.

amylopsin

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After 2 hours glucose levels go

back to normal

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After 30 min glucose levels

rise

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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

1. Symptoms present 2. Low blood glucose 3. 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