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Difficulty: HardEndocrinology and Metabolism

A 2020-year-old man with a history of type 11 diabetes mellitus is brought to the emergency department due to nausea, vomiting, abdominal pain, and increasing lethargy over the past 2424 hours. He recently had a mild upper respiratory tract infection. Vital signs show a temperature of 37.8∘C37.8^\circ\text{C} (100∘F100^\circ\text{F}), blood pressure of 90/6090/60 mm Hg, heart rate of 128128/min, and respiratory rate of 2828/min with deep, rapid breaths. Physical examination reveals dry mucous membranes and delayed capillary refill.

Initial laboratory results are as follows:

Laboratory TestResult
Serum glucose580580 mg/dL
Serum sodium132132 mEq/L
Serum potassium3.13.1 mEq/L
Serum bicarbonate1212 mEq/L
Arterial blood gas pH7.187.18
Serum ketonesPositive

Arrange the following therapeutic interventions in the most appropriate chronological sequence for the management of this patient.

  1. 1Rapid infusion of intravenous 0.9%0.9\% sodium chloride
  2. 2Intravenous potassium chloride supplementation
  3. 3Initiation of continuous intravenous regular insulin infusion
  4. 4Addition of 5%5\% dextrose to the intravenous fluid regimen
  5. 5Transition to subcutaneous basal and bolus insulin therapy

Answer

The correct sequence is: rapid infusion of normal saline, intravenous potassium chloride supplementation, continuous intravenous regular insulin infusion, addition of dextrose to IV fluids, and transition to subcutaneous insulin.
The management of diabetic ketoacidosis (DKA) follows a strict algorithmic sequence. 1) Fluid resuscitation with isotonic saline is the most critical initial step to restore perfusion. 2) Because this patient's potassium is severely low (<3.3< 3.3 mEq/L), potassium replacement must occur before insulin administration. 3) Once potassium is safe, continuous IV insulin is started to treat the acidosis. 4) Dextrose is added when glucose reaches 200−250200-250 mg/dL to avoid hypoglycemia while insulin continues to clear ketones. 5) Finally, subcutaneous insulin is overlapped before IV insulin is discontinued once the anion gap is fully closed.

Step-by-Step Solution

1
Assess the patient's volume status and begin fluid resuscitation.
The patient is hypotensive (90/6090/60 mm Hg) and tachycardic, indicating severe volume depletion. Intravenous 0.9%0.9\% sodium chloride is initiated first.
Restoring intravascular volume improves tissue perfusion and facilitates the renal clearance of glucose and ketones.
2
Evaluate the initial serum potassium level before initiating insulin therapy.
Serum potassium is 3.13.1 mEq/L. Potassium chloride is administered next, and insulin is temporarily withheld.
Insulin drives potassium into cells. Administering insulin when potassium is already <3.3< 3.3 mEq/L can precipitate fatal cardiac arrhythmias and respiratory muscle weakness.
3
Initiate insulin therapy once potassium is in a safe range (≥3.3\geq 3.3 mEq/L).
Continuous intravenous regular insulin is started.
Insulin is required to suppress lipolysis, halt ketogenesis, and resolve the underlying ketoacidosis.
4
Monitor blood glucose and adjust intravenous fluids accordingly.
When glucose drops below 200−250200-250 mg/dL, 5%5\% dextrose is added to the maintenance fluids.
This prevents hypoglycemia while allowing the continuation of the insulin infusion, which is still necessary to completely close the anion gap.
5
Determine readiness to transition off intravenous insulin.
Once the anion gap closes, pH normalizes, and the patient can eat, subcutaneous insulin is administered.
Subcutaneous insulin must be administered 11 to 22 hours prior to stopping the IV infusion to prevent rebound ketoacidosis.

Key Concept

In the management of diabetic ketoacidosis (DKA), if the initial serum potassium is <3.3< 3.3 mEq/L, insulin therapy must be delayed until potassium is aggressively replaced to prevent potentially fatal hypokalemia.
Estimated Time:1m 30s
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Topics

Endocrinology and Metabolism

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