Quiz 1: Glucose

Question 1

Methods of glucose metabolism regulation

Answer 1

1. Store glucose as a reservoir (glycogen) in Liver
   Moved to cells via Insulin
2. Mobilize the stored glucose to maintain the blood glucose levels
   Moved back to blood by hormones: glucagon, epinephrine, cortisol, Thyroxine, growth hormone

Question 2

Reactions For Determining Glucose

Answer 2

• Oxidation: glucose oxidase
• Phosphorylation:
hexokinase catalysis of ATP + glucose to ADP + G-6-P
• Oxidation reduction methods: copper reduction, ferricyanide
• Schiff’s Base formation with amines, glucose + Hgb to HgbA1C

Question 3

Hypoglycemia

Answer 3

• Hyperinsulinism: too much insulin, with an excessive amount of glucose is removed
May occur when a diabetic injects too much insulin:
Insulin shock may result in coma, glucose does not reach the brain
• Over stimulation of insulin: after heavily sugared food. Initial high glucose leves over-stimulates the pancreas, causing blood sugar levels to drop below normal after 2-3 hours.
• A Quick fix: (eating more sugar) causes more insulin production, Protein corrects by allowing glucose to enter bloodstream slowly

Question 4

Glucose Tolerance Testing

Answer 4

Establishes when glucose reaches the highest concentration and how rapidly it returns to normal levels.
• Patient is given specific amount of glucose (100g)
• Blood samples drawn at specific intervals: Fasting or Hourly intervals
• Detection of glucose in urine, (glycosuria)
Normal: doesn’t exceed 200 mg/dL, returns to 120 mg/dL after 2 hours
D. mellitus: peaks above 200 mg/dL, does not return to 120 mg/dL after 2 hours

Question 5

Function of Insulin

Answer 5

Increases the rate of glycolysis, glyogenesis, lipogenesis and synthesis of protein
Decreases rate of glycogenolysis and gluconeogensis
Lack of Insulin causes the opposite effect

Question 6

Ketoacidosis

Answer 6

• If carbohydrate metabolism is severely limited, the cell begins to oxidize fat reserves for energy.

• Proteins are degraded to amino acids leading to glucose
• Cells begin to oxidize fat reserves for energy, causes excess of AcetylCoA, which leads to excess ketone bodies, acidosis and can cause coma and death

Question 7

Glycosated Hgb Detection

Answer 7

• Glycosylated Hgb is formed when glucose reacts with the amino group of Hgb.
• The rate of formation is directly porportional to the plasma glucose concentration.
• Reflects the average blood glucose over the previous 2 to 3 months.

Question 8

Glycosated Hgb A1C Detection

Answer 8

• A minor component of Hgb to which glucose is bound
• Levels of Hgb A1C depend on blood glucose concentration
- The higher glucose = higher level of A1C
- Does not fluctuate with daily blood glucose levels
- Reflects an average glucose level over a 6 to 8 week period, can be used to diagnose Diabetes
Useful as indicator of how glucose level is controlled by drugs, diet, exercise with the normal range =

Question 9

Glycosated Hgb A1C Range

Answer 9

Normally <7%
HbA1c may be increased falsely in certain medical conditions: uremia (kidney failure), chronic excessive alcohol intake, and hypertriglyceridemia.
Falsely decrease HbA1c include acute or chronic blood loss, sickle cell disease or thalassemia.
Diabetes during pregnancy, commonly referred to as gestational diabetes, may falsely increase or decrease HbA1c.

Question 10

CSF Glucose Testing

Answer 10

• Normal CSF glucose = 60-80% of blood glucose level
- 450-800 mg/L (Kaplan pg 791), 40-70 mg/dL (Tietz 2006)
• Abnormal CSF glucose = (once equilibrated over 4 hrs) less than 40% of the blood glucose
• Distinguishes bacterial from viral meningitis
- Bacterial: glucose low, less than 40% of serum glucose
- Viral: glucose generally normal

Question 11

Most Commonly Preformed Glucose Tests

Answer 11

• Creatinine clearance vs glomerular filtration rate
• Urine osmolality for tubular concentration ability
• Urine protein electrophoresis: glomerular permeability and detection of Bence Jones Protein
• Serum creatinine and blood urea nitrogen (BUN) constant predictors of renal function

Question 12

Glucose’s Purpose in Body

Answer 12

Digestion, Metabolism, Regulation
End product of carbohydrate digestion in Intestine
Blood Glucose is maintained at a constant level by hormones (Insulin increases, all others decrease)

Question 13

Fasting Blood Glucose Reference Ranges

Answer 13

Reference Range for Serum/Plasma: 70-99mg/dL

Arterial and Capillary values are 2-3 mg/dL higher

Question 14

Hormones affecting Blood Glucose Levels

Answer 14

Insulin (increases) - produced by Beta cells in the pancreatic islets of Langerhans, promotes storage of glucose in Liver/Muscle/Adipose
Decrease:
Glucagon (Alpha cells of Pancreatic Islets of Langerhans, glycogenolysis and gluconeogenesis)
ACTH/Growth Hormone (secreted by anterior pituitary to raise blood glucose)
Cortisol (From Adrenal glands, stimulates glycogeno/lipolysis and gluconeogenesis)
Human Placental Lactogen
Epinephrine (medulla of adrenal glands, glycogeno/lipolysis and inhibits insulin secretion)
T3/T4 (Increases Glucose uptake in GI, glycogenolysis and gluconeogenesis)

Question 15

Diabetes Mellitus Diagnosis

Answer 15

Fasting Plasma Glucose > 126 mg/dL, Random Glucose > 200 mg/dL, 2 hr Peak Glucose > 200mg/dL, A1c > 6.5%

Question 16

Diabetes Monitoring Tests

Answer 16

Glycosylated Hgb, HbA1c
Fructotosamine
Urinary Microalbumin
C Peptide

Question 17

Urinary Microalbumin

Answer 17

Detects small amounts of albumin in urine to detect early renal damage

Question 18

C Peptide

Answer 18

Proinsulin is cleaved to produce C Peptide and Insulin

Shows level of endogenous Insulin production is patient is taking Insulin

Question 19

Gluconeogenesis

Answer 19

After 24-48 hours of fasting, glycogen stores are used up so Gluconeogenesis occurs