Creatinine before a contrast CT (iodinated contrast) or a gadolinium-enhanced MRI

Nephrology · Symptom or situation · updated 2026-10-31

BioMG follows French guidelines. Adapt it to the guidelines and the tests available where you practise.

Frequency: In France in 2022, diagnostic imaging amounted to 1 083 procedures per 1 000 beneficiaries of the national health insurance, of which 15.6% were CT scans (CT frequency up about 11% since 2017); the share of contrast-enhanced CT is not given ^[1].

Before a test with iodinated contrast (CT, angiography)

Laboratory tests

Serum creatinine with eGFR (CKD-EPI)if neededPatient at risk: known kidney disease (acute or chronic renal failure, renal surgery, proteinuria) or disease that can affect the kidney (lupus, etc.), hypertension, diabetes ^[2]. The ESUR adds hyperuricaemia and also accepts testing in all patients ^[3].
A result remains valid for 3 months in a stable patient, 7 days in an inpatient or a patient with an acute illness.

Detailed explanation and international comparison (in French): read it in English (machine translation)

Do not order

Testing for Bence Jones proteinuria before the injection in a patient with myeloma: not necessary ^[3].
Urine sample within 24 hours after the injection, or blood sample just afterwards in renal failure: the contrast agent can distort the assays; preferably sample before the injection ^[3].

After iodinated contrast in an at-risk patient

48 hours after the injection

Serum creatinine with eGFRif neededPatient at risk (GFR below the thresholds, acute renal failure) ^[3], or metformin stopped: restart it if renal function has not changed significantly ^[3], once reassessed and judged stable according to the SmPC ^[4].

Detailed explanation and international comparison (in French): read it in English (machine translation)

Before a gadolinium-enhanced MRI

No serum creatinine needed before a contrast-enhanced MRI.

Detailed explanation and international comparison (in French): read it in English (machine translation)

Do not order

Serum creatinine before a gadolinium MRI: not recommended by the SFR (no renal toxicity at the recommended doses, withdrawal of linear chelates at high risk of nephrogenic systemic fibrosis) ^[2]; not mandatory for the ESUR with low-risk agents ^[3].

Sources (9)