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Difficulty: HardEndocrinology and Metabolism

A 2222-year-old man with type 1 diabetes mellitus is brought to the emergency department with nausea, vomiting, generalized weakness, and confusion. Vital signs show blood pressure 90/60 mmHg90/60 \text{ mmHg}, heart rate 122/min122 \text{/min}, and respirations 28/min28 \text{/min} (deep and rapid). Fingerstick glucose is 550 mg/dL550 \text{ mg/dL}. Laboratory results show:

Sodium: 132 mEq/L132 \text{ mEq/L}
Potassium: 3.1 mEq/L3.1 \text{ mEq/L}
Chloride: 98 mEq/L98 \text{ mEq/L}
Bicarbonate: 10 mEq/L10 \text{ mEq/L}
BUN: 32 mg/dL32 \text{ mg/dL}
Creatinine: 1.4 mg/dL1.4 \text{ mg/dL}
Arterial pH: 7.157.15
Urine ketones: Large

Arrange the following steps in the most appropriate chronological sequence for the immediate and subsequent management of this patient's diabetic ketoacidosis.

  1. 1Administer rapid intravenous boluses of 0.9%0.9\% normal saline
  2. 2Administer intravenous potassium chloride
  3. 3Initiate a continuous intravenous regular insulin infusion
  4. 4Add 5%5\% dextrose to the intravenous fluids
  5. 5Transition to a subcutaneous basal-bolus insulin regimen

Answer

The correct sequence is to first administer intravenous fluids, followed by potassium chloride repletion, then initiate an intravenous insulin infusion, add dextrose to the fluids when glucose reaches 200 mg/dL200 \text{ mg/dL}, and finally transition to subcutaneous insulin once the anion gap closes.
The management of diabetic ketoacidosis (DKA) requires a strict, physiologically driven sequence. Initial treatment must focus on restoring intravascular volume with isotonic saline to reverse severe dehydration and improve renal perfusion. After initiating fluid resuscitation, serum potassium must be evaluated. In this patient, the potassium is 3.1 mEq/L3.1 \text{ mEq/L}. Because insulin shifts potassium intracellularly, administering insulin before replacing potassium can cause profound hypokalemia and fatal arrhythmias. Therefore, potassium chloride must be given before starting insulin. Once potassium is ≥3.3 mEq/L\geq 3.3 \text{ mEq/L}, a continuous intravenous regular insulin infusion is started to halt ketogenesis and correct the metabolic acidosis. As the blood glucose drops to approximately 200 mg/dL200 \text{ mg/dL}, 5%5\% dextrose is added to the intravenous fluids. This allows the insulin infusion to be maintained (to clear the remaining ketones) without causing hypoglycemia, ensuring the anion gap fully closes. Finally, once the anion gap has closed and the patient is able to eat, intravenous insulin is transitioned to a subcutaneous regimen for long-term management.

Step-by-Step Solution

1
Assess volume status and provide immediate resuscitation with 0.9%0.9\% normal saline.
Restores intravascular volume and improves tissue perfusion.
Patients with diabetic ketoacidosis are profoundly dehydrated due to osmotic diuresis; volume resuscitation is the universally accepted first step.
2
Evaluate the potassium level and administer potassium chloride.
Prevents life-threatening hypokalemia.
The patient's initial potassium is 3.1 mEq/L3.1 \text{ mEq/L}. Insulin cannot be started until potassium is ≥3.3 mEq/L\geq 3.3 \text{ mEq/L} because insulin shifts potassium intracellularly.
3
Start a continuous intravenous regular insulin infusion.
Halts lipolysis, ketogenesis, and begins to correct the acidosis.
Insulin is required to suppress the production of ketoacids and allow the cells to utilize glucose, thereby closing the anion gap.
4
Monitor glucose and add 5%5\% dextrose to the intravenous fluids when glucose reaches ≈200 mg/dL\approx 200 \text{ mg/dL}.
Maintains euglycemia while acidosis continues to clear.
The metabolic acidosis typically takes longer to resolve than the hyperglycemia. Adding dextrose prevents hypoglycemia while allowing the necessary continuous insulin infusion.
5
Discontinue intravenous insulin and transition to subcutaneous insulin.
Provides long-term maintenance management.
Once the anion gap has closed and the patient is able to eat, the patient is stabilized and can be safely transitioned off the intravenous infusion (ensuring an overlap period).

Key Concept

The precise, stepwise algorithmic management of Diabetic Ketoacidosis (DKA) with severe initial hypokalemia.
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Topics

Endocrinology and Metabolism

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