In acute kidney injury, which acid-base disturbance is commonly observed?

• A. Metabolic alkalosis with hypokalemia
• B. Metabolic acidosis with hyperkalemia
• C. Respiratory acidosis with hyperkalemia
• D. No acid-base disturbance

Answer: (B)

In acute kidney injury, the kidneys’ ability to excrete hydrogen ions and regenerate bicarbonate is impaired, while potassium excretion also decreases. This combination leads to metabolic acidosis because bicarbonate falls and hydrogen ions accumulate in the blood. At the same time, reduced distal tubule potassium secretion and the acidosis-driven shift of potassium from cells into the extracellular space cause hyperkalemia. The body may try to compensate by increasing respiration to blow off CO2, but without sufficient kidney function the acid–base disturbance remains prominent. This pattern—metabolic acidosis with elevated potassium—is a typical finding in AKI, whereas metabolic alkalosis, a primary respiratory problem, or no disturbance would not fit the kidney’s compromised ability to handle acid and potassium.