Hypoglycemia (SACCM) Flashcards
Cite three sources of glucose
- Intestinal absorption from digestion of carbohydrates
- Breakdown of the storage form (glycogen) via glycogenolysis
- Production of glucose from precursos: Lactate, aa, pyruvate and glycerol, via gluconeogenesis
List hormones that elevate the concentration of glucose in plasma
Glucagon
Epinephrine
Cortisol
Growth hormone
What are the stimulants of insuline secretion from the B cells in the pancreas
- Increased concentrations of glucose after a meal
- increased concentrations of aminoacids after a meal
- increased GI hormones: gastrin, secretin, cholecystokinin and specially gastric inhibitory peptide
What are the precursors of glucose
Lactate, pyruvate, amino acids and glycerol (gluconeogenesis)
Describe the inhibitory function of insulin (3)
Insulin inhibits gluconeogenesis, glycogenolysis and decreases glucagon secretion
Describe the stimulatory function of insulin (5)
- 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
What hormones are released in the event of hypoglycemia? Specify the timeline
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
Which cells secrete glucagon?
Pancreatic alpha cells
Functions of glucagon (4)
It acts on the liver to:
1. stimulate hepatic glycogenolysis
2. and gluconeogenesis
3. mobilizes gluconeogenic precursors
4. reduces peripheral glucose utilization
Give 2 effects for each hormone regarding glucose homeostasis:
Epinephrine, cortisol and growth hormone
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
What are the 4 mechanisms of hypoglycemia
- Inadequate dietary intake (requires another mechanism)
- excessive glucose utilization
- dysfunctional glycogenolytic, gluconeogenic pathways or inadequate precursors for these pathways.
- endocrine abnormalities
Which organ relies the most on glucose? what are the clinical manifestations
The brain, neuroglycopenia
dullness/obtundation, weakness, ataxia, seizures, blindness
Causes of hypoglycemia (at least 10!)
- 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
What percentage of hepatic function is enough to maintain euglycemia ?
Approximately 30% ( you need to lose 70% of function to show signs of hypoglycemia)
Mechanism of hypoadrenocorticism related hypoglycemia
Loss of cortisol induced counterregulatory mechanisms:
- increases glucose facilitating lipolysis
- release of aminoacids from the muscle for gluconeogenesis in the liver
