Electrolyte Disorders USMLE Step 1 Practice Question
A 38-year-old man with untreated type 1 diabetes mellitus presents with polyuria, abdominal pain, and deep rapid breathing. Laboratory studies show glucose 540 mg/dL, potassium 5.8 mEq/L, bicarbonate 9 mEq/L, and arterial pH 7.12. After insulin treatment is started, his potassium falls rapidly. Which of the following best explains his initial elevated serum potassium before therapy?
Answer choices
- ADecreased aldosterone secretion from autoimmune adrenalitis
- BRelease of potassium from rhabdomyolysis
- CRenal potassium retention from loop diuretic use
- DShift of potassium out of cells due to acidemia and insulin deficiencyCorrect answer
- ETotal body potassium excess from increased intake
- FImpaired renal potassium excretion from acute kidney injury secondary to hyperglycemic hyperosmolarity
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