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Difficulty: Very hardEndocrinology and Metabolism

A 2424-year-old man with a history of type 1 diabetes mellitus is brought to the emergency department with abdominal pain, vomiting, and confusion. Laboratory evaluation reveals the following:

Laboratory TestResultReference Range
Serum glucose580 mg/dL580 \text{ mg/dL}70−99 mg/dL70-99 \text{ mg/dL}
Arterial pH7.157.157.35−7.457.35-7.45
Serum bicarbonate9 mEq/L9 \text{ mEq/L}22−28 mEq/L22-28 \text{ mEq/L}
Serum potassium3.0 mEq/L3.0 \text{ mEq/L}3.5−5.0 mEq/L3.5-5.0 \text{ mEq/L}
Anion gap26 mEq/L26 \text{ mEq/L}8−12 mEq/L8-12 \text{ mEq/L}

He is diagnosed with severe diabetic ketoacidosis (DKA). Arrange the following management steps in the most appropriate chronological sequence for this patient.

  1. 1Infuse 11 to 22 liters of 0.9%0.9\% sodium chloride intravenously.
  2. 2Administer intravenous potassium chloride.
  3. 3Initiate a continuous intravenous infusion of regular insulin.
  4. 4Add 5%5\% dextrose to the intravenous fluids.
  5. 5Transition to a subcutaneous basal-bolus insulin regimen.

Answer

The correct sequence is: 1) Infuse 0.9% sodium chloride, 2) Administer intravenous potassium chloride, 3) Initiate intravenous regular insulin, 4) Add 5% dextrose to IV fluids, and 5) Transition to subcutaneous insulin.
The standard management sequence for DKA prioritizes ABCs and fluid resuscitation. Therefore, IV normal saline is always first. The next critical decision point is the potassium level. Because this patient's potassium is dangerously low at 3.0 mEq/L3.0 \text{ mEq/L}, potassium replacement must occur before insulin is given. Once potassium is ≥3.3 mEq/L\geq 3.3 \text{ mEq/L}, continuous IV insulin is started. When blood glucose drops to approximately 200 mg/dL200 \text{ mg/dL}, 5%5\% dextrose is added to the IV fluids to allow continued insulin administration for ketone clearance without causing hypoglycemia. Finally, after the anion gap is closed (≤12 mEq/L\leq 12 \text{ mEq/L}) and the patient can eat, IV insulin is transitioned to a subcutaneous regimen.

Step-by-Step Solution

1
Assess volume status and initiate immediate fluid resuscitation.
Administration of 0.9%0.9\% sodium chloride.
The patient is profoundly dehydrated due to osmotic diuresis; volume expansion is always the immediate first step in DKA management.
2
Evaluate the serum potassium level before administering insulin.
Administration of intravenous potassium chloride.
The patient has severe hypokalemia (3.0 mEq/L3.0 \text{ mEq/L}). Insulin drives potassium intracellularly; administering insulin now would precipitate fatal cardiac arrhythmias. Potassium must be replaced first.
3
Begin insulin therapy once the potassium level is safe (≥3.3 mEq/L\geq 3.3 \text{ mEq/L}).
Initiation of intravenous regular insulin infusion.
Insulin halts ketogenesis and lipolysis, correcting the underlying acidosis and lowering blood glucose.
4
Monitor blood glucose and adjust intravenous fluids accordingly.
Addition of 5%5\% dextrose to the IV fluids once glucose drops to ≤200 mg/dL\leq 200 \text{ mg/dL}.
This prevents hypoglycemia. The insulin drip must remain on to clear the ketones and close the anion gap.
5
Transition to maintenance therapy.
Transition to a subcutaneous insulin regimen.
This is done once the anion gap closes, acidosis resolves, and the patient can tolerate an oral diet.

Key Concept

In the management of diabetic ketoacidosis (DKA), profound hypokalemia (<3.3 mEq/L< 3.3 \text{ mEq/L}) requires immediate potassium replacement prior to the initiation of insulin therapy to prevent fatal cardiac arrhythmias.
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Topics

Endocrinology and Metabolism

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