Which factor increases the risk of contrast-induced nephropathy?

Which factor increases the risk of contrast-induced nephropathy?

• A. Younger age
• B. Recent nephrotoxic medications
• C. Pre-existing renal impairment
• D. Use of non-iodinated contrast

Answer: (C)

Kidney function status largely drives risk: pre-existing renal impairment greatly increases the chance of contrast-induced nephropathy. When the kidneys already have reduced GFR or nephron reserve, the introduction of iodinated contrast can push them toward acute injury. The contrast can cause afferent arteriolar vasoconstriction, lowering renal blood flow, especially in the outer medulla, and it can also have direct tubular toxicity. In a kidney with compromised function, these insults are more likely to cause a noticeable decline in filtration. Other factors fit less well. Being younger usually means better renal reserve, so risk is lower rather than higher. Recent nephrotoxic medications can raise risk, but the strongest and most consistent predictor is already-existing renal impairment. Using non-iodinated contrast generally does not carry the same risk because the nephrotoxic mechanism is linked to iodinated contrast exposure.

Kidney function status largely drives risk: pre-existing renal impairment greatly increases the chance of contrast-induced nephropathy. When the kidneys already have reduced GFR or nephron reserve, the introduction of iodinated contrast can push them toward acute injury. The contrast can cause afferent arteriolar vasoconstriction, lowering renal blood flow, especially in the outer medulla, and it can also have direct tubular toxicity. In a kidney with compromised function, these insults are more likely to cause a noticeable decline in filtration.

Other factors fit less well. Being younger usually means better renal reserve, so risk is lower rather than higher. Recent nephrotoxic medications can raise risk, but the strongest and most consistent predictor is already-existing renal impairment. Using non-iodinated contrast generally does not carry the same risk because the nephrotoxic mechanism is linked to iodinated contrast exposure.