- Rise of serum creatinine of ≥0.5 mg/dL or 25% above baseline within 48 hours after parenteral contrast administration.
- Majority of cases are nonoliguric.
- Peak in serum creatinine usually occurs within 3–5 days with complete resolution in 7–10 days for most patients.
- Oliguria and need for dialysis are unusual and are primarily seen in patients with diabetes with severe chronic kidney disease.
Contrast-induced nephropathy (CIN) is a common cause of hospital-acquired acute renal failure. Although the incidence of CIN is low, the number of patients receiving intravenous contrast media is enormous and is expected to rise as the population ages and greater numbers of patients will be subjected to diagnostic and therapeutic procedures requiring intravascular contrast.
Observational retrospective studies have demonstrated that patients incurring CIN had significantly higher in-hospital mortality than counterparts who did not develop CIN, particularly so if they went on to need dialysis. Multivariate regression analysis, adjusting for baseline differences in comorbidities, strongly suggests that CIN is, in fact, an independent predictor of mortality.
Various patient and procedural factors influence the likelihood of developing CIN. Among patient-related factors, preexisting chronic kidney disease (CKD) is regarded as the most potent risk factor. Nearly 60% of patients developing CIN have baseline CKD, and the incidence of CIN parallels the severity of prestanding renal impairment. Diabetes mellitus also confers increased risk of developing CIN, but only in patients with CKD. Thus the risk of CIN is greatest in patients with CKD and diabetes, lower in nondiabetic patients with CKD, and lowest in patients without preexisting CKD regardless of their diabetic status. Similarly, patients with CKD and diabetes are at the highest risk of developing oliguric acute renal failure and of requiring dialysis. Patients with CIN who require dialysis have a very high in-hospital mortality.
Volume depletion, congestive heart failure, older age, and hypotension have all been cited as risk factors for CIN but are probably primarily markers for a low glomerular filtration rate (GFR), the true risk factor. Concomitant use of nephrotoxins such as nonsteroidal anti-inflammatory agents also increase the risk for CIN.
Multiple myeloma has traditionally been considered a risk factor for CIN. However, recent studies using modern contrast agents indicate that patients with multiple myeloma are not at a greater risk, provided that they are volume replete at the time of contrast exposure.
Procedure-related factors will also influence the likelihood of CIN. Most studies, although not all, suggest that exposure to larger volumes of parenteral contrast causes greater predisposition to CIN. In addition, the type of contrast material (specifically its osmolality) influences the development of CIN. Contrast media formulations occur in three types: High-osmolar contrast media (also termed ionic), which have an osmolality of approximately 2000 mOsm/L, low-osmolar contrast media (also termed nonionic), which have an osmolality of 600–900 mOsm/L, and iso-osmolar contrast media (also a nonionic composition), which have an osmolality of 300 mOsm/L (Figure 12–1...