Metformin Monitoring and Change in Serum Creatinine Levels in Patients Undergoing Radiologic Procedures Involving Administration of Intravenous Contrast Media

Study Objectives. To evaluate the prevalence and magnitude of serum creatinine level elevations in patients receiving metformin who underwent radiologic procedures involving administration of intravenous contrast media, and to evaluate the efficacy of an electronic consultation in promoting timely evaluation of renal function after the procedure. Design. Retrospective evaluation. Setting. Veterans Affairs Medical Center. Patients. Ninety-seven patients receiving metformin who underwent a radiologic procedure involving administration of intravenous contrast media over a 27-month period. Measurements and Main Results. Ninety-seven patients underwent a total of 111 radiologic procedures with documented administration of intravenous contrast dye. Average time from procedure to laboratory follow-up, excluding one patient, was 2.62 ± 1.56 days. Average serum creatinine levels before and after the procedure were 1.10 ± 0.19 and 1.13 ± 0.23 mg/dl, respectively (p>0.05). Four patients developed contrast material-associated nephropathy. An additional four patients with borderline serum creatinine levels at baseline (1.4 mg/dl) had a serum creatinine level of 1.5 mg/dl or greater after the procedure. Conclusion. Our results indicated that electronic consultations result in timely evaluation of serum creatinine levels in patients receiving metformin who undergo a radiologic procedure involving intravenous contrast material. Also, the study suggests that nearly 4% of patients with diabetes mellitus and normal renal function may develop contrast material–associated neuropathy with nonionic contrast material. In addition, about 8% of patients with diabetes treated with metformin (with baseline serum creatinine levels < 1.5 mg/dl) who undergo a procedure with nonionic intravenous contrast material acquire an increased risk (serum creatinine ≥ 1.5 mg/dl) of lactic acidosis. These findings support the recommendations of the Food and Drug Administration regarding metformin monitoring in patients undergoing radiologic procedures involving administration of intravenous contrast media.