Endocrine & Metabolic Emergencies Flashcards
What are endogenous steroids synthesized from?
Cholesterol
What are two examples of hydrophilic compounds (water soluble)?
Peptides and catecholamines
What are two examples of lipophilic compounds (lipid soluble)?
- Steroids and thyroid hormones
- Circulate in blood bound to plasma proteins
- This binding greatly slows their clearance from plasma
What is the hypothalamic pituitary axis?
- A major neuroendocrine system
- Main stress response
- Relationship and interaction between hypothalamus, pituitary gland, and target organs
How does the HPA exert its effect?
In response to corticotropin releasing hormone (CTRH) from the hypothalamus, the anterior pituitary gland secretes adrenocorticotropic hormone (ACTH), which acts on the cortex of the adrenal gland to secrete cortisol to the body
What is the hypothalamus? (In relation to the HPA)
- The coordinating center of much of the endocrine system
- It consolidates signals from the body and then delivers precise signals to the pituitary gland
What hormones are secreted by the anterior portion of the pituitary gland? (adenohypophysis)
- TSH: thyroid stimulating hormone
- ACTH: adrenocorticoptropic hormone
- LH: luteinizing hormone
- GH: growth hormone
- Prolactin
- FSH: follicle stimulating hormone
What hormones are secreted by the posterior portion of the pituitary gland? (neurohypophysis)
- ADH
- Oxytocin
What part of the pancreas secretes insulin?
The beta cells of the islets of Langerhans
What are the acinar cells?
The functional unit of the exocrine pancreas that synthesizes, stores, and secretes digestive enzymes
What are the 4 cell types in the pancreas and what do they secrete?
- Alpha = glucagon
- Beta = secrete insulin
- Delta = somatostatin
- F = pancreatic polypeptide
What population of veterinary patients are most likely to develop DM?
- Dogs 4-14 years old
- Females are twice as likely
- Male neutered cats >6y
Describe Type 1 DM
- Primary insulin dependent
- Destruction of beta cells
- Require insulin for life
- Almost all dogs and 50-70% of cats develop Type 1
Describe Type 2 DM
- Non insulin dependent DM (NIDDM)
- Uncommon in dogs
- Results from insulin resistance, dysfunctioning beta cells, and increased hepatic gluconeogenesis
Does Type 2 DM progress to ketoacidotic states?
No
Can NIDDM cats progress to IDDM?
Yes
What is secondary diabetes?
- Development of carbohydrate intolerance secondary to concurrent insulin resistant disease
- Pregnancy, Cushings
What diet should be promoted for DM?
- Diet high in carbs with fiber
- Fiber helps promote weight loss and slows absorption of glucose from GIT, which helps reduce the post prandial flux of glucose
- High protein diet for cats
What does the fructosamine test indicate?
- Fructosamine is formed by glycosylation (the reaction in which a carb is attached to another molecule to form a glycoconjugate) of serum proteins such as albumin
- Evaluates BG over a matter of weeks
- Normal 225-360 umol/L
- > 500 suggests inadequate control of DM
What is the Somogyi phenomenon?
- Characterized by episodes of hypoglycemia, followed by rebound hyperglycemia
- Indicates that the insulin dose is too high
- Suspect if clinical signs of DM are present with fructosamine levels <400
What are the 3 types of ketones?
- Beta-hydroxybutyrate
- Acetoacetate
- Acetate
How do ketones form?
- Normally, fatty acids are released from adipose tissue, oxidized by liver, and formed into triglycerides via ‘beta oxidation’
- Without insulin, the fatty acids are converted to ketones
How do ketones cause an osmotic diuresis?
Ketones and glucose begin spilling into the urine; the secretion of ketones drags along positively charged ions (Na, K), which causes increased loss of fluid and salt
Why is lipemia sometimes seen in DKA?
Because of the increase in free fatty acids, because without insulin, the lipoprotein lipase is not activated
Why does hyponatremia occur in DKA?
An increase in osmoles within circulation draws fluid into the vascular space, resulting in dilution of Na
Do glucose and ketones improve with IVFT alone?
- Glucose: yes
- Ketones: no. Insulin required
Why does hypophosphatemia occur in DKA?
Phos shifts into the ICS like K
Why is dextrose administered to DKA patients?
It is vital to achieve metabolic breakdown of ketone bodies and resolve acidosis
How long does ketone resolution take?
~3 days