Internal Medicine Exam Diabetic Ketoacidosis Management 4 — Questions and Answers
Question 1: In DKA, the serum potassium is initially high despite total body potassium depletion. What is the primary mechanism?
- Increased potassium absorption from the gut
- Acidosis-driven transcellular shift of potassium out of cells (Correct answer)
- Reduced renal potassium excretion
- Aldosterone deficiency causing potassium retention
Correct answer: Acidosis-driven transcellular shift of potassium out of cells
Metabolic acidosis causes H⁺ to shift into cells in exchange for K⁺ moving out, raising serum potassium despite total body depletion.
Question 2: A patient with DKA has serum phosphate of 0.8 mg/dL. In which clinical scenario would phosphate replacement be most strongly indicated?
- Any DKA patient with detectable ketonuria
- Symptomatic hypophosphatemia with cardiac dysfunction or respiratory failure (Correct answer)
- Serum phosphate < 2.0 mg/dL in all patients
- All DKA patients as part of routine repletion
Correct answer: Symptomatic hypophosphatemia with cardiac dysfunction or respiratory failure
Phosphate replacement is indicated in DKA when hypophosphatemia is symptomatic or associated with cardiac/respiratory dysfunction.
Question 3: Which finding best differentiates DKA from hyperglycemic hyperosmolar state (HHS)?
- Serum glucose > 600 mg/dL
- Effective serum osmolality > 320 mOsm/kg
- Anion gap metabolic acidosis with significant ketonemia (Correct answer)
- Absence of altered mental status
Correct answer: Anion gap metabolic acidosis with significant ketonemia
DKA is characterized by significant ketonemia and anion gap acidosis, whereas HHS has minimal or no ketosis.
Question 4: What is the expected rate of glucose decline per hour with appropriate insulin therapy in DKA?
- 25–50 mg/dL/hr
- 50–75 mg/dL/hr (Correct answer)
- 100–150 mg/dL/hr
- Over 200 mg/dL/hr
Correct answer: 50–75 mg/dL/hr
Optimal insulin therapy lowers blood glucose by 50–75 mg/dL per hour; faster drops risk cerebral edema especially in children.
Question 5: A patient with DKA on insulin infusion develops glucose of 180 mg/dL but still has an anion gap of 20. What is the appropriate management?
- Stop insulin and reassess in 2 hours
- Switch to subcutaneous insulin immediately
- Add dextrose to IV fluids and continue insulin infusion (Correct answer)
- Reduce insulin infusion by 50%
Correct answer: Add dextrose to IV fluids and continue insulin infusion
When glucose reaches 200–250 mg/dL but the anion gap remains elevated, add dextrose to maintain glucose while continuing insulin to clear ketones.
Question 6: Which laboratory test provides the most accurate real-time assessment of ketone clearance in DKA?
- Urine ketones by dipstick
- Serum acetoacetate level
- Serum beta-hydroxybutyrate level (Correct answer)
- Urine specific gravity
Correct answer: Serum beta-hydroxybutyrate level
Serum beta-hydroxybutyrate directly measures the predominant ketone in DKA and is more accurate than urine dipstick or acetoacetate alone.
Question 7: A patient with known type 1 diabetes is NPO for surgery scheduled tomorrow morning. How should insulin be managed to prevent DKA?
- Hold all insulin until after surgery
- Continue basal insulin at full dose; hold prandial insulin (Correct answer)
- Switch to sliding scale only
- Give 50% of total daily dose as regular insulin q6h
Correct answer: Continue basal insulin at full dose; hold prandial insulin
Basal insulin should be continued (sometimes at 75–80% dose) during NPO periods to prevent DKA; prandial insulin is held when there is no oral intake.
Internal Medicine Exam Diabetic Ketoacidosis Management 4
In DKA, the serum potassium is initially high despite total body potassium depletion.
What is the primary mechanism?