Fluctuations in eGFR in relation to unenhanced and enhanced MRI and CT outpatients.

OBJECTIVE: To study fluctuations in estimated glomerular filtration rate (eGFR) in relation to contrast medium (CM) enhanced magnetic resonance imaging (MRI) and computed tomography (CT) compared to control groups in outpatients.

MATERIALS AND METHODS: eGFR was determined right before the imaging procedure and three days later at the department or at the patient's home. The iodine-based and gadolinium-based contrast media were the same as used for all other examinations at the department.

RESULTS: A total of 716 patients completed the study. There was a statistically significant, but not clinically relevant rise in eGFR after three days in all four groups. The average eGFR variation was 4.8 ml/min/1.73 m(2). There were large variations in eGFR between the two measurements in 45.8% of the patients as they had a change greater than ± 10 ml/min/1.73 m(2). Only three patients fulfilled the contrast-induced nephropathy (CIN) requirement when the definition s-creatinine ≥ 44 μmol/l (0.5mg/dl) was used.

CONCLUSIONS: eGFR in outpatients undergoing MRI or CT did vary independently of whether the patient received contrast or not. The findings probably reflect the natural variations in s-creatinine levels. This should be taken into consideration when CIN is studied.