OVERVIEW

What is contrast-induced nephropathy?

Contrast-induced nephropathy refers to a rapid decline in kidney function within 24–48 hours after intravascular injection of contrast media, characterized by a significant increase in serum creatinine levels compared to pre-contrast values, excluding other causes of renal impairment. This reversible kidney injury is known as contrast-induced nephropathy.

How likely is contrast-induced nephropathy to occur?

The reported incidence of contrast-induced nephropathy varies widely, depending on the presence of risk factors such as chronic kidney disease (CKD), especially diabetic nephropathy, the dose and type of contrast agent administered, and the specific radiological procedure.

Additional risk factors include renal hypoperfusion due to heart failure, hypovolemia or hemodynamic instability, and multiple myeloma.

SYMPTOMS

What are the common manifestations of contrast-induced nephropathy?

Kidney injury may occur within minutes of contrast exposure. However, clinical manifestations such as oliguria or elevated serum creatinine are typically observed 24–48 hours after contrast exposure. Most patients are non-oliguric.

This condition usually presents as acute renal failure, with serum creatinine increasing by >25% or rising by more than 0.5 mg/dl compared to pre-contrast levels. Urine output may decrease significantly or remain normal. The elevated serum creatinine typically declines spontaneously within 3–7 days, followed by a return to or near pre-contrast kidney function.

Can contrast-induced nephropathy lead to serious consequences?

The acute kidney injury caused by this condition may be accompanied by hyperkalemia, acidosis, etc. In rare cases, dialysis may be required.

CAUSES

Which contrast agents may cause contrast-induced nephropathy?

The contrast agents that cause this condition are mostly iodine-containing preparations, including four types: nonionic low-osmolar, ionic low-osmolar, nonionic iso-osmolar, and ionic high-osmolar.

Compared with ionic high-osmolar agents, nonionic low-osmolar, ionic low-osmolar, and nonionic iso-osmolar contrast agents pose a lower risk of contrast-induced nephropathy.

Which populations are more susceptible to contrast-induced nephropathy?

Individuals with pre-existing conditions such as renal failure, hypertension, heart failure, diabetes, multiple myeloma, as well as advanced age, high-dose contrast agent use, or the use of high-osmolar contrast agents, have an increased risk of developing this condition.

DIAGNOSIS

What tests are needed to diagnose contrast-induced nephropathy?

Urinalysis, renal function tests, renal ultrasound.

What is the purpose of the relevant tests for contrast-induced nephropathy?

• Urinalysis: Used to assess kidney damage and identify other potential causes of renal injury. Microscopic examination of urine sediment may reveal typical signs of acute tubular necrosis (ATN), including muddy brown granular casts, epithelial cell casts, and shed renal tubular epithelial cells.

• Renal function tests: The primary indicator for diagnosing contrast-induced nephropathy. In nearly all cases, an increase in creatinine (reflecting reduced glomerular filtration rate, GFR) occurs within 24–48 hours after contrast administration and is usually mild. Creatinine levels typically begin to decline within 3–7 days.

• Renal ultrasound: Used to evaluate kidney morphology and structure, as well as rule out other causes of renal injury.

Which diseases is contrast-induced nephropathy easily confused with?

This condition can be distinguished from ischemic acute tubular necrosis and acute interstitial nephritis based on medical history and the aforementioned laboratory tests.

Is a kidney biopsy necessary for diagnosing contrast-induced nephropathy?

Kidney biopsy is generally not helpful in diagnosing contrast-induced nephropathy because the lesions of acute tubular necrosis (ATN) are focal and nonspecific, and contrast-induced acute kidney injury (AKI) is usually transient.

TREATMENT

Which department should I visit for contrast-induced nephropathy?

Nephrology.

How should contrast-induced nephropathy be treated?

As mentioned earlier, in most patients with contrast-induced nephropathy, serum creatinine—one of the indicators of kidney function—begins to decrease within 3–7 days and eventually returns to or near pre-contrast levels. Only a very small number of patients experience persistent kidney damage.

In rare cases, patients may require dialysis due to acute kidney injury caused by contrast agents.

There is no specific medication for this condition, making prevention more important than treatment.

DIET & LIFESTYLE

Can patients with contrast-induced nephropathy have normal fertility?

Yes.

Is contrast-induced nephropathy hereditary?

No. This disease is caused by contrast agents and is not hereditary.

PREVENTION

Can Contrast-Induced Nephropathy Be Prevented?

Yes.

• Use the lowest possible dose of contrast medium and opt for non-ionic, iso-osmolar, or low-osmolar contrast agents.

• Avoid repeated contrast administration within 48–72 hours, prevent volume depletion, and discontinue NSAIDs 24–48 hours before the procedure.

• Administer intravenous saline hydration before and after contrast exposure.