Hypoglycemia (SACCM)

Question 1

Cite three sources of glucose

Answer 1

1. Intestinal absorption from digestion of carbohydrates
2. Breakdown of the storage form (glycogen) via glycogenolysis
3. Production of glucose from precursos: Lactate, aa, pyruvate and glycerol, via gluconeogenesis

Question 2

List hormones that elevate the concentration of glucose in plasma

Answer 2

Glucagon
Epinephrine
Cortisol
Growth hormone

Question 3

What are the stimulants of insuline secretion from the B cells in the pancreas

Answer 3

1. Increased concentrations of glucose after a meal
2. increased concentrations of aminoacids after a meal
3. increased GI hormones: gastrin, secretin, cholecystokinin and specially gastric inhibitory peptide

Question 4

What are the precursors of glucose

Answer 4

Lactate, pyruvate, amino acids and glycerol (gluconeogenesis)

Question 5

Describe the inhibitory function of insulin (3)

Answer 5

Insulin inhibits gluconeogenesis, glycogenolysis and decreases glucagon secretion

Question 6

Describe the stimulatory function of insulin (5)

Answer 6

• It promotes glycogen storage
• stimulates glucose uptake
• Utilization by insulin - sensitive cells
• promotes tryglyceride formation in adipose tissue
• Promotes the synthesis of protein and glycogen in muscle

Question 7

What hormones are released in the event of hypoglycemia? Specify the timeline

Answer 7

Epinephrine, glucagon, cortisol and growth hormone
- Epi and glucagon within minutes and have a transient effect
- Cortisol ahd GH within few hours and have a longer lasting effect up to 12 hours

Question 8

Which cells secrete glucagon?

Answer 8

Pancreatic alpha cells

Question 9

Functions of glucagon (4)

Answer 9

It acts on the liver to:
1. stimulate hepatic glycogenolysis
2. and gluconeogenesis
3. mobilizes gluconeogenic precursors
4. reduces peripheral glucose utilization

Question 10

Give 2 effects for each hormone regarding glucose homeostasis:
Epinephrine, cortisol and growth hormone

Answer 10

Epinephrine:
- limits insulin secretion
- increases glucagon secretion
Cortisol:
- increases glucose facilitating lipolysis
- release of aminoacids from the muscle for gluconeogenesis in the liver
Growth hormone antagonizes effects of insulin by
- decreasing peripheral glucose
- and promoting lipolysis

Question 11

What are the 4 mechanisms of hypoglycemia

Answer 11

1. Inadequate dietary intake (requires another mechanism)
2. excessive glucose utilization
3. dysfunctional glycogenolytic, gluconeogenic pathways or inadequate precursors for these pathways.
4. endocrine abnormalities

Question 12

Which organ relies the most on glucose? what are the clinical manifestations

Answer 12

The brain, neuroglycopenia
dullness/obtundation, weakness, ataxia, seizures, blindness

Question 13

Causes of hypoglycemia (at least 10!)

Answer 13

• Artifact: hemoconcentration
• Excess insulin (or analogus)
  
  • exogenous overdose
  • Insulinoma
  • Pareneoplastic syndrome
  • Toxins or meds
• Excess utilization
  
  • Infection
  • Exercise
  • polycytemia
  • leukocytosis
  • pregnancy
  • exercise induced
• Decreased glucose products
  
  • Neonatal
  • Hepatic dysfunction
  • Hypocortisolism
  • Hormone deficiencies: glucagon, GF,
    thyroid horm, cathecolamines,
    hypopituitarism
  • Glycogenic or gluconeogenic enz
    deficiencies
  • Beta blockers

Question 14

What percentage of hepatic function is enough to maintain euglycemia ?

Answer 14

Approximately 30% ( you need to lose 70% of function to show signs of hypoglycemia)

Question 15

Mechanism of hypoadrenocorticism related hypoglycemia

Answer 15

Loss of cortisol induced counterregulatory mechanisms:
- increases glucose facilitating lipolysis
- release of aminoacids from the muscle for gluconeogenesis in the liver

Question 16

Drugs for medical managment of persistent hypoglycemia (chronic) due to insulinoma:
1. Med – MOA
2. Med – MOA
… (5)

Answer 16

1. Prednisone: cortisole analogus
2. Diazoxide: inhibits pancreatic insulin secretion
3. Streptozocin: selectively destroys the B cells of the pancreas
4. Octreotide (somatostatin analogus ): suppresses synthesis and secretion of insulin.
5. Alloxan: Beta cell cytotoxin