Endocrine 1 - Diabetes, Thyroid, and OB Flashcards
Where is the endogenous peptide called Insulin synthesized?
pancreatic beta cells
What are three functions of Insulin?
facilitate transport of glucose and potassium into cells
shift metabolism toward storage (glycogen, lipid synthesis)
stimulates protein synthesis (anabolism)
How much insulin per hour is secreted when the body is at rest?
How much insulin per day is secreted in response to food, stress, corticosteroids, and other stimuli?
1 unit/hr at rest
40-50 units/day when stressed
Which pancreatic cell when stimulated DECREASES insulin production?
Which pancreatic cell when stimulated INCREASES insulin production?
Alpha DECREASES Beta INCREASES (parasympathetic stim also increases insulin)
Why is it more effective to administer a 1-2 unit/hr continuous infusion of insulin rather than a large bolus?
Insulin receptors get saturated at low insulin concentrations.
Why does insulin have a sustained effect of 30-60 mins?
Insulin is tightly bound to receptors
What is the half-time of Insulin?
5-10 mins
What is the biggest risk when administering exogenous insulin?
Hypoglycemia
What is the Pre-op management recommendation for your patient who takes insulin daily?
No short-acting insulin on day of surgery a partial (half) dose of long-acting insulin implanted pumps should either be discontinued or on continuous infusion
How much does 1 unit of exogenous insulin lower plasma glucose by in a normal adult?
25-30mg/dL
How quickly does 1 unit of IV insulin start to work, what is the peak effect, and how long does 1 unit last?
onset: 10 mins, Peak: 15-30 mins, duration: 30-60 mins
What is the recommended starting rate of infusion for insulin?
0.1 units/kg/hr or Plasma Glucose (mg/dL)/150
What pancreatic cells secrete Glucagon?
alpha cells
What stimuli trigger glucagon secretion?
hypoglycemia, stress, trauma, cortisol, sepsis
What is mobilized into the systemic circulation when glucagon is stimulated?
glucose, fatty acids, amino acids, and increased liver production of glucose
What drug is not a catecholamine but acts like one by increasing cAMP, myocardial contractility, SV, HR and works even in the presence of Beta-blockade?
Glucagon
What are some side effects of glucagon?
nausea/vomiting and hypoglycemia
What is the elimination half-time of glucagon?
3-6 mins
What are some examples of Sulfonylureas?
GLIpizIDE (Glucotrol), GLYburIDE(Micronase), GLImepirIDE (Amaryl)
What class of drugs is the first line treatment for Type II diabetes?
Sulfonylureas
What is the mechanism of action of Sulfonylureas?
increases beta cell activity leading to more insulin secretion
What class of drug does metformin (glucophage) fall in?
Biguanides (oral hypoglycemic agents)
What is the mechanism of action of metformin?
inhibits hepatic gluconeogenesis by preventing the convertion of lactate into glucose
What are some risks associated with metformin?
lactic acidosis and low risk for hypoglycemia
True or false: Metformin should be held on the day of surgery?
True, but lacks supporting evidence
What is the mechanism of action of Thiazolidinediones (TZDs) (ex: Actos)?
decreases insulin resistance at the skeletal muscle/adipose tissue making the body more sensitive to insulin
What is the mechanism of action of Sitagliptin (Januvia)?
inhibits DPP-4 which increases insulin release and decreases hepatic glucose production.
Should your patient who has been fasting for several hours before surgery be given the okay to take their oral hypoglycemic agent on the day of surgery?
No, but taking their med the day of surgery depends on how long its been without caloric intake. Daily regimen can often be maintained if first surgery of the day.
