ITE Diabetic Ketoacidosis and HHS — Questions and Answers
Question 1: A patient with DKA has a serum potassium of 5.8 mEq/L on presentation. When should potassium supplementation be initiated?
- Immediately with insulin infusion
- When potassium falls below 5.5 mEq/L (Correct answer)
- When potassium falls below 3.5 mEq/L
- Only after anion gap closes
Correct answer: When potassium falls below 5.5 mEq/L
Potassium supplementation should be added to IV fluids when serum K+ falls below 5.5 mEq/L to prevent hypokalemia from insulin-driven cellular uptake.
Question 2: Which of the following best explains the mechanism of anion gap metabolic acidosis in DKA?
- Lactic acid accumulation from tissue hypoperfusion
- Accumulation of beta-hydroxybutyrate and acetoacetate (Correct answer)
- Loss of bicarbonate through the kidneys
- Hyperchloremia from normal saline administration
Correct answer: Accumulation of beta-hydroxybutyrate and acetoacetate
DKA causes anion gap acidosis due to accumulation of ketoacids (beta-hydroxybutyrate and acetoacetate) from unregulated fatty acid oxidation.
Question 3: A 28-year-old with type 1 DM presents with DKA. Blood glucose is 420 mg/dL and beta-hydroxybutyrate is elevated. After 8 hours of treatment, glucose is 180 mg/dL but pH remains 7.15 and anion gap is still elevated. What is the most appropriate next step?
- Increase insulin infusion rate
- Add dextrose to IV fluids and continue insulin (Correct answer)
- Stop insulin and reassess in 2 hours
- Administer sodium bicarbonate
Correct answer: Add dextrose to IV fluids and continue insulin
When glucose falls below 200-250 mg/dL before anion gap closes, dextrose should be added to IV fluids to allow continuation of insulin until ketoacidosis resolves.
Question 4: What is the most common precipitating factor for DKA in patients with established type 1 diabetes?
- New onset diabetes
- Infection or illness
- Insulin omission (Correct answer)
- Myocardial infarction
Correct answer: Insulin omission
Insulin omission (non-adherence) is the most common precipitating cause of DKA in patients with known type 1 diabetes.
Question 5: A patient with HHS has a serum osmolality of 345 mOsm/kg and blood glucose of 1100 mg/dL. Which IV fluid is most appropriate for initial resuscitation?
- 0.45% NaCl (hypotonic saline)
- 0.9% NaCl (isotonic saline) (Correct answer)
- D5W (5% dextrose in water)
- Lactated Ringer's solution
Correct answer: 0.9% NaCl (isotonic saline)
Isotonic normal saline (0.9% NaCl) is used first in HHS to restore circulating volume before transitioning to hypotonic fluids for free water replacement.
Question 6: Which laboratory finding would most strongly suggest HHS rather than DKA in a hyperglycemic patient?
- Serum glucose > 600 mg/dL
- Serum osmolality > 320 mOsm/kg
- Absence of significant ketonemia with pH > 7.3 (Correct answer)
- Blood urea nitrogen > 30 mg/dL
Correct answer: Absence of significant ketonemia with pH > 7.3
The hallmark distinguishing feature of HHS from DKA is the absence of significant ketoacidosis (pH > 7.3, bicarbonate > 18 mEq/L, minimal ketonemia).
Question 7: A patient recovering from DKA develops worsening headache, confusion, and pupillary changes 6 hours into treatment. What is the most likely diagnosis?
- Hypokalemia-induced arrhythmia
- Cerebral edema (Correct answer)
- Hypoglycemia from insulin overdose
- Septic encephalopathy
Correct answer: Cerebral edema
Cerebral edema is a life-threatening complication of DKA treatment, most common in children, caused by rapid fluid shifts and osmotic changes during correction.
Question 8: A 55-year-old with type 2 DM on an SGLT2 inhibitor presents with fatigue, nausea, and blood glucose of 210 mg/dL. pH is 7.20, bicarbonate 12, and urine ketones are large. What is this presentation called?
- Starvation ketosis
- Alcoholic ketoacidosis
- Euglycemic DKA (Correct answer)
- Hyperosmolar hyperglycemic state
Correct answer: Euglycemic DKA
Euglycemic DKA, associated with SGLT2 inhibitors, presents with ketoacidosis but relatively normal blood glucose due to glycosuria and altered glucagon/insulin ratio.
Question 9: What is the target rate of serum glucose reduction during the initial phase of DKA treatment?
- 25-50 mg/dL per hour
- 50-75 mg/dL per hour (Correct answer)
- 75-100 mg/dL per hour
- Greater than 100 mg/dL per hour
Correct answer: 50-75 mg/dL per hour
The recommended rate of glucose reduction in DKA is 50-75 mg/dL per hour to avoid rapid osmotic shifts that could precipitate cerebral edema.
Question 10: Which of the following is the most appropriate insulin regimen for mild DKA (pH 7.25-7.30, patient alert and tolerating oral intake)?
- Subcutaneous rapid-acting insulin only (Correct answer)
- IV insulin infusion at 0.1 units/kg/hr
- Subcutaneous basal-bolus insulin regimen
- No insulin; treat with IV fluids alone
Correct answer: Subcutaneous rapid-acting insulin only
Mild DKA in a patient able to eat can be managed with subcutaneous rapid-acting insulin alone rather than IV infusion, per ADA guidelines.
Question 11: A patient with DKA has a corrected sodium of 148 mEq/L. How is corrected sodium calculated in hyperglycemia?
- Add 1.6 mEq/L for every 100 mg/dL glucose above 100 (Correct answer)
- Add 2.4 mEq/L for every 100 mg/dL glucose above 100
- Subtract 1.6 mEq/L for every 100 mg/dL glucose above 100
- No correction needed; measure directly
Correct answer: Add 1.6 mEq/L for every 100 mg/dL glucose above 100
Corrected sodium is calculated by adding 1.6 mEq/L (or 2.4 mEq/L per some guidelines) for every 100 mg/dL glucose above 100 to account for osmotic dilution.
Question 12: A patient with DKA has a serum phosphate of 1.1 mg/dL. Which complication is most closely associated with severe hypophosphatemia in DKA?
- Cardiac arrhythmias
- Respiratory muscle weakness and hemolytic anemia (Correct answer)
- Seizures
- Acute kidney injury
Correct answer: Respiratory muscle weakness and hemolytic anemia
Severe hypophosphatemia in DKA can cause respiratory muscle weakness, hemolysis, and rhabdomyolysis, though routine phosphate replacement is not recommended.
Question 13: When transitioning from IV insulin to subcutaneous insulin at the end of DKA treatment, what is the most important timing consideration?
- Stop IV insulin immediately when anion gap closes
- Give subcutaneous long-acting insulin 2 hours before stopping IV insulin (Correct answer)
- Overlap subcutaneous and IV insulin for 30 minutes only
- Wait until the patient is eating a full meal before any subcutaneous dose
Correct answer: Give subcutaneous long-acting insulin 2 hours before stopping IV insulin
Long-acting subcutaneous insulin should be administered at least 2 hours before stopping IV insulin to prevent recurrence of ketoacidosis due to insulin gap.
Question 14: In DKA, which of the following best explains the Kussmaul breathing pattern seen on examination?
- Pulmonary edema from aggressive fluid resuscitation
- Respiratory compensation for metabolic acidosis (Correct answer)
- Central neurogenic hyperventilation from cerebral edema
- Diaphragm weakness from hypokalemia
Correct answer: Respiratory compensation for metabolic acidosis
Kussmaul respirations (deep, labored breathing) represent the respiratory system's attempt to blow off CO2 and compensate for the severe metabolic acidosis of DKA.
