Which of the following is NOT listed as a likely cause of hyperkalemia?

• A. Renal failure
• B. Missed dialysis
• C. Trauma (crush injury)
• D. Dehydration

Answer: (D)

Potassium balance is driven mainly by renal excretion and shifts of potassium between inside and outside cells. The most direct ways to raise serum potassium are: the kidneys can’t excrete it (renal failure), a patient relies on dialysis and misses a session (potassium builds up), or potassium is released from cells into the bloodstream (as in crush injuries). Dehydration, on the other hand, tends to promote processes that drive potassium out of the body, not keep it in. Aldosterone increases with volume depletion to conserve sodium and water, which increases potassium secretion in the distal nephron, making hyperkalemia less likely. So dehydration is not a typical cause of hyperkalemia, while renal failure, missed dialysis, and crush injuries are.