Contrast Agents

Question 1

Type of AKI caused by use of iodinated contrast agents for cardiovascular and CT imaging:

Answer 1

Contrast nephropathy

Question 2

People with normal renal function are equally at risk with CKD patients in developing contrast nephropathy. T or F?

Answer 2

False. The risk of AKI, or “contrast nephropathy,” is negligible in those with normal renal function but increases in the setting of CKD, particularly diabetic nephropathy.

Question 3

The most common clinical course of contrast

nephropathy is characterized by:

Answer 3

a rise in SCr beginning 24–48 h following exposure,
peaking within 3–5 days, and
resolving within 1 week

Question 4

More severe, dialysis-requiring AKI is uncommon except in the setting
of:

Answer 4

-Significant preexisting CKD
-Multiple myeloma and renal disease are particularly
susceptible

Question 5

Common findings in contrast nephropathy

Answer 5

• Low fractional excretion of sodium (FeNa)

- relatively benign urinary sediment without features of tubular necrosis

Question 6

Contrast nephropathy is thought to occur

from a combination of factors, including (3):

Answer 6

(1) hypoxia in the renal outer medulla
- due to perturbations in renal microcirculation and occlusion
of small vessels;
(2) cytotoxic damage to the tubules
- directly or via the generation of oxygen-free radicals, especially because the concentration of the agent within the tubule is markedly increased; and
(3) transient tubule obstruction with precipitated contrast material.

Question 7

Other diagnostic agents implicated as a cause of AKI

Answer 7

• high-dose gadolinium (used for magnetic resonance imaging (MRI)
• oral sodium phosphate solutions (used as bowel purgatives)