Lecture 10: Endocrinology CIS

Question 1

GLUT-2 vs. GLUT-4

Answer 1

GLUT-2: facilitative glucose transporter located in plasma membrane of the liver, pancreatic, intestinal, kidney cells and portal/hypothalamus areas. Has low affinity and high capacity for dietary sugars.

GLUT-4: is insulin-DEPENDENT and responsible for the majority of glucose transport into muscle and adipose cells in anabolic conditions

Question 2

How do we calculate anion gap; what does it tell us; what is normal range?

Answer 2

• Anion Gap = Na+ - (Cl- + HCO3-)
• Normal = 10-12 mM/L
• Quantity of anions not balanced by cations.
• Usually due to the negatively charged plasma proteins

Question 3

What occurs in Diabetic Ketoacidosis; using each letter D-K-A explain

Answer 3

D: glucose >250 mg/dL

K: serum positive for ketones

A: metabolic acidosis with blood pH <7.3; serum HCO3- <15mEq/L

Question 4

What are common labs indicative of DKA?

Answer 4

• Hyperglycemia
• Hyperkalemia
• Hyponatremia
• Low [HCO3-]
• Decreased pH
• High anion gap
• Ketonuria
• Increased plasma osmolality
• Elevated BUN and creatinine (azotemia)

Question 5

Which labs should be ordered to confirm diagnosis of T1DM?

Answer 5

• C-peptide
• β-hydroxybutyrate
• HbA1c

Question 6

DKA is commonly associated w/ what type of diabetes and what are the 2 most common causes?

Answer 6

• Affilitated with T1DM
  1) Failure to take insulin (leading cause)
  2) Stressors to the system: trauma, infection (UTI and pneumonia), medications
• Increased epinephrine blocks insulin’s actions w/ stimulation of glucagon activity

Question 7

Which respiratory sign can be indicative of ketoacidosis?

Answer 7

Kussmaul respirations to compensate for acidosis

Question 8

Why is their osmotic diuresis in hyperglycemia and DKA?

Answer 8

• Increased glucose to the proximal tubule of kidney overwhelms its capacity for absorption
• Increased osmotic pressure of renal tubular fluid
• Decreased water reabsorption
• Dehydration
• Decreased excretion of ketones = ketonemia

Question 9

What causes the metabolic acidosis in DKA?

Answer 9

• β-hydroxybutyrate and acetoacetic acid are ketones produced that are strong acids and dissociate freely in H+ ions
• Overproduction of H+ ions overwhelms the buffering capacity of the body