In the presence of a reduced nephron mass, the remaining nephrons are vulnerable to injury. Iodinated contrast, after causing a brief (minutes) period of vasodilation, causes sustained (hours to days) intrarenal vasoconstriction and ischemic injury. The ischemic injury sets off a cascade of events largely driven by oxidative injury causing death of renal tubular cells. If a sufficient mass of nephron units are affected, then a recognizable rise in serum creatinine will occur.

Contrast-induced acute kidney injury (AKI) was defined as serum creatinine increase of 25% and/or 0.5 mg/dl and is shown separately for patients with (solid circles) and without (open circles) diabetes. CrCl = creatinine clearance; eGFR = estimated glomerular filtration rate. Data adapted from McCullough et al. (12).

Relative risk reductions (RRRs) are for iso-osmolar (IOCM) compared with low-osmolar contrast media (LOCM). CKD = baseline chronic kidney disease defined as an estimated creatinine clearance <60 ml/min; DM = diabetes mellitus. Data adapted from McCullough et al. (47).

ACS = acute coronary syndromes; bid = twice daily; Cr = creatinine; DM = diabetes mellitus; IV = intravenous; NAC = N-acetylcysteine; NSAIDs = nonsteroidal anti-inflammatory drugs; PGE₁ = prostaglandin E₁; po = by mouth; other abbreviations as in Figure 2.