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Difficulty: EasyGeneral Internal Medicine

A 2424-year-old woman with type 11 diabetes mellitus presents to the emergency department with abdominal pain, nausea, and Kussmaul respirations. She is diagnosed with diabetic ketoacidosis. Her initial laboratory results demonstrate a serum glucose of 600600 mg/dL and a serum potassium of 5.85.8 mEq/L. She is tachycardic and hypotensive.

Arrange the following interventions in the correct chronological order as her treatment progresses over the next several hours.

  1. 1Administer a rapid bolus of intravenous normal saline (0.9%0.9\% NaCl)
  2. 2Initiate a continuous intravenous regular insulin infusion
  3. 3Add potassium chloride to the intravenous fluids when serum potassium falls below 5.25.2 mEq/L
  4. 4Add 5%5\% dextrose to the intravenous fluids when serum glucose falls below 250250 mg/dL

Answer

The correct sequence is: 1) Administer intravenous normal saline, 2) Initiate an intravenous regular insulin infusion, 3) Add potassium chloride when serum potassium falls below 5.2 mEq/L, and 4) Add 5% dextrose when serum glucose falls below 250 mg/dL.
The algorithmic management of diabetic ketoacidosis requires immediate intravascular volume expansion with normal saline to correct severe dehydration and improve tissue perfusion. Once fluids are running, intravenous regular insulin is started to halt lipolysis and ketogenesis. As insulin drives glucose and potassium into cells, serum potassium levels will predictably fall; thus, potassium chloride is added to the fluids once the level drops below 5.25.2 mEq/L to prevent dangerous hypokalemia. Finally, because the anion gap typically takes longer to close than the time it takes for glucose to normalize, 5%5\% dextrose is added to the fluids once serum glucose reaches 200−250200-250 mg/dL. This allows the continuation of the insulin infusion to clear ketones without causing hypoglycemia.

Step-by-Step Solution

1
Analyze the patient's presentation and baseline laboratory values.
The patient has diabetic ketoacidosis with severe hyperglycemia, hyperkalemia, and signs of intravascular volume depletion.
Establishing the baseline hemodynamic and electrolyte status is required to safely sequence the treatment steps.
2
Identify the primary and most immediate life-saving intervention.
Administer a rapid bolus of intravenous normal saline.
Severe osmotic diuresis leads to profound dehydration. Restoring intravascular volume improves tissue perfusion and begins to lower glucose via renal clearance.
3
Determine the next pharmacologic step to reverse the underlying pathophysiology.
Initiate a continuous intravenous regular insulin infusion.
Because the initial potassium is elevated, it is safe to start insulin immediately after fluids to halt lipolysis and ketone production.
4
Anticipate the complications of insulin therapy and target electrolyte replacement.
Add potassium chloride when serum potassium falls below 5.25.2 mEq/L.
Total body potassium is depleted in diabetic ketoacidosis. As insulin shifts potassium into cells, serum levels will fall rapidly and require timely supplementation.
5
Determine the intervention needed when serum glucose begins to normalize but ketones persist.
Add 5%5\% dextrose when serum glucose falls below 250250 mg/dL.
Ketone clearance (closing the anion gap) takes longer than glucose normalization. Dextrose prevents hypoglycemia while allowing insulin to continue working.

Key Concept

The standard sequential management of diabetic ketoacidosis prioritizes immediate volume resuscitation, followed by insulin therapy, targeted electrolyte replacement, and eventually glucose supplementation to prevent hypoglycemia while clearing ketones.
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General Internal Medicine

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