Which renal process acts as a compensatory mechanism in respiratory acidosis?

Which renal process acts as a compensatory mechanism in respiratory acidosis?

• A. Hypoventilation
• B. Decreased reabsorption of bicarbonate by the kidneys
• C. Increased Na+/H+ exchange by the kidneys
• D. Decreased ammonia formation by the kidneys

Answer: (C)

In respiratory acidosis, CO2 builds up and lowers pH, so the kidneys shift into a buffering mode: they excrete more hydrogen ions and reclaim bicarbonate to raise the pH. A major renal step is upregulating the tubular Na+/H+ exchanger, which increases H+ secretion into the urine in exchange for Na+. This enhances acid removal and promotes the formation and reabsorption of bicarbonate back into the blood, helping to restore normal pH. Ammonia production also increases to provide additional buffering, but the key process highlighted here is the increased Na+/H+ exchange. The other options aren’t renal compensatory mechanisms: hypoventilation is the cause of the problem, not a kidney response; decreasing bicarbonate reabsorption would worsen acidosis; and decreasing ammonia formation would reduce buffering rather than compensate.

In respiratory acidosis, CO2 builds up and lowers pH, so the kidneys shift into a buffering mode: they excrete more hydrogen ions and reclaim bicarbonate to raise the pH. A major renal step is upregulating the tubular Na+/H+ exchanger, which increases H+ secretion into the urine in exchange for Na+. This enhances acid removal and promotes the formation and reabsorption of bicarbonate back into the blood, helping to restore normal pH. Ammonia production also increases to provide additional buffering, but the key process highlighted here is the increased Na+/H+ exchange. The other options aren’t renal compensatory mechanisms: hypoventilation is the cause of the problem, not a kidney response; decreasing bicarbonate reabsorption would worsen acidosis; and decreasing ammonia formation would reduce buffering rather than compensate.