Hypoglycemia

Question 1

What organ controls glucose homeostasis?

Answer 1

liver

• controls glycogenolysis, gluconeogenesis, and glycogenesis
• stores and releases glucose

Question 2

How much of liver mass is required to maintain euglycemia?

Answer 2

30%

Question 3

What is the difference between glucose and glycogen?

Answer 3

glucose - soluble, able to be transported in the blood

glycogen - insoluble, stored in the liver

Question 4

What hormones control gluconeogenesis and glycogenesis?

Answer 4

• stress hormones, like cortisol and glucagon stimulate gluconeogenesis and inhibit glycogenesis
• insulin inhibits gluconeogenesis and stimulates glycogenesis

Question 5

What is glycogenolysis? What stimulates and inhibits it?

Answer 5

glycogen in the liver is broken down into glucose for utilization

• stimulated by glucagon from alpha cells in the pancreas
• inhibited by insulin from beta cells

Question 6

What are the 6 common signs of hypoglycemia?

Answer 6

1. lethargy
2. weakness
3. ataxia
4. bizarre behavior
5. seizures
6. coma

episodic, present from days to months (usually 1-6 months)

Question 7

What are 5 causes of hypoglycemia?

Answer 7

1. liver failure
2. sepsis
3. hypoadrenocorticism (cortisol = gluconeogenesis, glycogenolysis)
4. xylitol toxicity (high dose can cause liver failure and necrosis)
5. insulin overdose

Question 8

In what animals is hypoglycemia more common?

Answer 8

• juveniles: small glucose stores due to development of liver, require specialized diet
• hunting dogs
• toy breeds

Question 9

What neoplasia can cause hypoglycemia? Why?

Answer 9

• insulinoma
• leiomyoma
• hepatocellular carcinoma

secrete insulin-like substances or destroy the liver

Question 10

What is an insulinoma?

Answer 10

beta-cell tumor that secretes insulin regardless of blood glucose levels less than 60 mg/dL

Question 11

What is the most common signalment associated with insulinomas?

Answer 11

middle-aged to older, medium to large dogs with no sex predilection

Question 12

What are the 7 major differential diagnoses for hypoglycemia?

Answer 12

1. insulinoma
2. hepatoma, leiomyoma, sarcoma
3. liver failure
4. insulin, oral hypoglycemics
5. sepsis
6. hypoadrenocorticism
7. xylitol toxicity

Question 13

What are the 2 types of juvenile hypoglycemia?

Answer 13

1. neonatal - <6 wks
2. transient juvenile - toy breeds

Question 14

What are the 4 major parts of the work up for patients with hypoglycemia?

Answer 14

1. AUS
2. bile acids - liver function
3. basal cortisol - hypoadrenocorticism
4. insulin and glucose levels - <60 mg/dL

Question 15

What imaging is used to help diagnose causes of hypoglycemia?

Answer 15

• radiology: r/o other diseases
• ultrasound
• CT

Question 16

How is paired measurements of blood glucose and insulin interpreted?

Answer 16

measure insulin when BG <60 mg/dL

• BG <60, insulin > normal = insulinoma
• BG <60, insulin upper 50% RI = insulinoma
• BG <60, insulin lower 50% RI = maybe insulinoma
• BG <60, insulin below normal = not insulinoma

Question 17

What diet alterations are used to treat hypoglycemia?

Answer 17

• high fat, protein, and complex carbs (Dextrose solutions)
• multiple small meals

Question 18

What 2 medical treatments are recommended for treating hypoglycemia?

Answer 18

1. glucocorticoids - Prednisone
2. Diazoxide - blocks pancreatic insulin release and glucose uptake by tissues and stimulates hepatic gluconeogenesis (severe GI side effects)

Question 19

What treatment is most recommended for insulinoma treatment? What 2 complications are associated?

Answer 19

surgery —> diagnostic and therapeutic

1. pancreatitis
2. DM

Question 20

What is the prognosis of insulinoma treatment like?

Answer 20

• short-term = good; surgery survival is 1-2 yrs, medical survival is 6 months
• long-term = guarded to poor, almost 100% chance of metastasis