Which type of acute kidney injury is most commonly due to decreased renal perfusion?

• A. Decreased renal perfusion
• B. Obstruction
• C. Intrinsic kidney disease
• D. Kidney stone

Answer: (A)

The type of acute kidney injury most tied to decreased renal perfusion is prerenal AKI. When blood flow to the kidneys falls—due to dehydration, blood loss, heart failure, or systemic hypotension—the kidneys receive insufficient filtration pressure, so the glomerular filtration rate drops. The body responds by conserving volume and activating mechanisms like the renin–angiotensin–aldosterone system, which helps maintain perfusion but can lead to oliguria if the problem isn’t corrected. Clinically, prerenal AKI is the most common cause of AKI, especially in hospitalized patients, and labs often show a relatively high BUN-to-creatinine ratio and concentrated urine with low sodium, reflecting preserved tubular function early on.

Other options describe problems that aren’t about reduced renal perfusion. Obstruction and kidney stones cause postrenal AKI, where urine flow is blocked after the kidney, leading to a buildup of pressure. Intrinsic kidney disease involves damage within the kidney itself (like acute tubular necrosis or glomerulonephritis) rather than an issue with blood flow.