Before administering iodinated contrast, which test helps assess kidney function?

Before administering iodinated contrast, which test helps assess kidney function?

• A. Creatinine clearance
• B. Urine albumin-to-creatinine ratio
• C. Serum creatinine
• D. Urinalysis for infection

Answer: (C)

Evaluating kidney function before iodinated contrast focuses on estimating how well the kidneys can filter waste. Serum creatinine is the practical and standard marker used to assess this. A blood test for creatinine is used to estimate the glomerular filtration rate (eGFR), which directly reflects how well the kidneys are filtering at baseline. If the eGFR is reduced, the patient is at higher risk for contrast-related kidney injury, and clinicians may adjust plans (use less contrast, ensure hydration, or choose alternatives). Other tests don’t measure current filtration as directly. Creatinine clearance requires a timed urine collection and is less convenient in routine pre-contrast checks. The urine albumin-to-creatinine ratio detects kidney damage from protein leakage but doesn’t reliably indicate current filtration capacity. Urinalysis for infection checks for infection, not kidney function. So the blood creatinine (to estimate eGFR) best informs the risk assessment before giving iodinated contrast.

Evaluating kidney function before iodinated contrast focuses on estimating how well the kidneys can filter waste. Serum creatinine is the practical and standard marker used to assess this. A blood test for creatinine is used to estimate the glomerular filtration rate (eGFR), which directly reflects how well the kidneys are filtering at baseline. If the eGFR is reduced, the patient is at higher risk for contrast-related kidney injury, and clinicians may adjust plans (use less contrast, ensure hydration, or choose alternatives).

Other tests don’t measure current filtration as directly. Creatinine clearance requires a timed urine collection and is less convenient in routine pre-contrast checks. The urine albumin-to-creatinine ratio detects kidney damage from protein leakage but doesn’t reliably indicate current filtration capacity. Urinalysis for infection checks for infection, not kidney function. So the blood creatinine (to estimate eGFR) best informs the risk assessment before giving iodinated contrast.