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Difficulty: HardEndocrinology and Metabolism

A 24-year-old woman with type 1 diabetes mellitus is brought to the emergency department due to a 2-day history of severe nausea, vomiting, and abdominal pain. She has not taken her insulin because she was unable to keep food down. Her blood pressure is 90/60 mmHg90/60\text{ mmHg}, pulse is 125/min125/\text{min}, and respirations are 28/min28/\text{min} and deep. Laboratory results show:

Serum glucose: 580 mg/dL580\text{ mg/dL}
Serum sodium: 132 mEq/L132\text{ mEq/L}
Serum potassium: 3.0 mEq/L3.0\text{ mEq/L}
Serum chloride: 98 mEq/L98\text{ mEq/L}
Serum bicarbonate: 10 mEq/L10\text{ mEq/L}
Arterial blood gas pH: 7.157.15
Urine ketones: positive (+++)

Arrange the following management steps in the most appropriate chronological sequence for this patient.

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

Answer

The correct sequence is: IV normal saline, then IV potassium chloride, then IV regular insulin infusion, then add dextrose to IV fluids, and finally transition to subcutaneous insulin.
The correct chronological management of this DKA presentation begins with volume resuscitation using 0.9%0.9\% normal saline to address hypotension and dehydration. Next, because the serum potassium is critically low at 3.0 mEq/L3.0\text{ mEq/L} (below the 3.3 mEq/L3.3\text{ mEq/L} threshold), potassium must be aggressively repleted before any insulin is administered. Once potassium levels are deemed safe, an IV regular insulin infusion is started to halt ketoacid production and close the anion gap. As the insulin works, serum glucose drops faster than the anion gap closes; therefore, 5%5\% dextrose is added to the IV fluids when glucose reaches 200 to 250 mg/dL200\text{ to }250\text{ mg/dL} to prevent hypoglycemia while insulin continues. Finally, once the anion gap has closed and the patient is eating, treatment transitions to a subcutaneous insulin regimen.

Step-by-Step Solution

1
Assess hemodynamic status and restore volume.
Initial administration of 0.9%0.9\% normal saline.
The patient is hypotensive and tachycardic. Isotonic saline restores intravascular volume and renal perfusion, which is universally the first step in diabetic ketoacidosis (DKA) management.
2
Evaluate electrolytes, specifically serum potassium.
Identify potassium level of 3.0 mEq/L3.0\text{ mEq/L} and administer IV potassium chloride.
Total body potassium is depleted in DKA despite often normal serum levels. This patient is already severely hypokalemic (<3.3 mEq/L< 3.3\text{ mEq/L}). Giving insulin would drive potassium into cells and cause life-threatening arrhythmias, so potassium must be repleted first.
3
Address insulin deficiency and ketoacidosis.
Initiate IV regular insulin infusion.
Once potassium is ≥3.3 mEq/L\geq 3.3\text{ mEq/L}, insulin is required to drive glucose into cells, stop lipolysis, and resolve the anion gap acidosis.
4
Monitor glucose and adjust fluids during insulin therapy.
Add 5%5\% dextrose to the maintenance IV fluids.
Glucose levels fall faster than ketone levels. Dextrose is added when glucose reaches 200 to 250 mg/dL200\text{ to }250\text{ mg/dL} to allow continued insulin administration for ketone clearance without causing hypoglycemia.
5
Plan for definitive, maintenance therapy.
Transition to subcutaneous basal-bolus insulin.
This is done when the anion gap is closed, acidosis is resolved (pH >7.3> 7.3, HCO3 >15 mEq/L> 15\text{ mEq/L}), and the patient can tolerate oral feeding.

Key Concept

Diabetic ketoacidosis (DKA) management sequencing, particularly the critical requirement to delay insulin therapy until profound hypokalemia (<3.3 mEq/L< 3.3\text{ mEq/L}) is corrected.
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Topics

Endocrinology and Metabolism

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