A 45-year-old male with type 1 diabetes mellitus arrives at the emergency department with complaints of excessive thirst, frequent urination, nausea, and confusion. On examination, he appears dehydrated, with Kussmaul breathing (deep, rapid respirations) and fruity breath odour. Which electrolyte imbalance is most commonly associated with acute diabetic ketoacidosis (DKA)?

Appeared in: NORCET-7 Mains-2024

Explanation

In the acute phase of DKA, metabolic acidosis causes hydrogen ions (H+) to move into cells for buffering.
To maintain electrical neutrality, potassium ions (K+) shift out of the cells and into the bloodstream, leading to elevated serum potassium levels (hyperkalemia).
The lack of insulin further contributes to hyperkalemia, as insulin is necessary to help move potassium from the blood into the cells.
Although serum potassium is high, the total body potassium is depleted due to significant urinary losses from osmotic diuresis.

Option B: This is a major risk during the treatment of DKA, not typically at initial presentation. Insulin and fluid therapy drive potassium back into cells, causing a rapid drop in serum levels.
Option C: DKA typically causes pseudohyponatremia (falsely low sodium). High blood glucose pulls water from cells into the blood, diluting the serum sodium concentration.
Option D: DKA is a defining example of metabolic acidosis, caused by the accumulation of acidic ketone bodies, which lowers the blood pH.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Electrolyte and Acid-Base Imbalances in Diabetic Ketoacidosis (DKA) as background academic context rather than a clinical decision trigger.
Recognizing that initial hyperkalemia masks a total body potassium deficit is critical for safe DKA management. Starting insulin without addressing potassium levels can induce life-threatening cardiac arrhythmias from hypokalemia.
The nurse's priority is to check the initial potassium level before starting insulin. If the level is low (e.g., below 3.3 mEq/L), insulin therapy must be delayed, and potassium replacement initiated first.
Continuous cardiac monitoring (ECG) is essential to watch for signs of hyperkalemia (peaked T waves) or hypokalemia (flattened T waves, U waves).

How to Approach the Question

First, identify the clinical picture in the stem. The combination of excessive thirst, Kussmaul breathing, and fruity breath in a patient with type 1 diabetes points directly to Diabetic Ketoacidosis (DKA).
Next, recall the core pathophysiological disturbances of DKA: Hyperglycemia, Ketosis, and Metabolic Acidosis.
Focus on the 'Acidosis' component. Remember that in an acidotic state, the body attempts to buffer by shifting H+ ions into cells.
Recall the principle of electroneutrality: as the positive H+ ions enter cells, other positive ions, primarily K+, must leave the cells and enter the bloodstream.
This cellular shift leads to an increase in serum potassium, making hyperkalemia the expected initial finding, even though the body's total potassium is depleted.
Evaluate the options based on this understanding. Eliminate metabolic alkalosis (DKA is acidosis), hypernatremia (hyponatremia is more common), and hypokalemia (a risk of treatment, not presentation).

Concept Tested & Keywords

Concept Tested: Electrolyte and Acid-Base Imbalances in Diabetic Ketoacidosis (DKA)
Stem keywords: diabetic ketoacidosis, DKA, type 1 diabetes, electrolyte imbalance, Kussmaul breathing
Lead-in keywords: most commonly associated with
Clinical cues: excessive thirst
Clinical cues: frequent urination

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E6 Medicine Davidson Principles Practice 24e p. 756-758

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 199-201

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Attempt every question from this paper in a timed mock, then review the full solution for each one.