Which statement best distinguishes acute kidney injury from chronic kidney disease in terms of onset and reversibility?

• A. AKI is rapid and reversible; CKD is gradual and irreversible.
• B. CKD is gradual and irreversible; AKI is rapid and reversible.
• C. AKI is rapid and often reversible; CKD is gradual and typically irreversible.
• D. Both are rapid and reversible.

Answer: (C)

Acute kidney injury shows up suddenly—over hours to days—usually from a temporary problem such as dehydration, low blood flow, infection, or exposure to kidney-toxic substances. Because the insult can be removed or corrected, kidney function often recovers, though not always completely. Chronic kidney disease, on the other hand, develops slowly over months to years as permanent structural damage accumulates, and the lost function is typically not fully reversible, with gradual progression over time.

So, the best statement is that AKI is rapid and often reversible, while CKD is gradual and typically irreversible. The idea that AKI is always fully reversible is too absolute, since some cases don’t recover completely, and CKD is not rapid or reversible.