Severe Complications from an Unexpectedly High Serum Mycophenolic Acid Concentration in a Patient with Renal Failure Secondary to Lupus Nephritis: A Case Report

Mycophenolate mofetil (MMF) is used widely to treat lupus nephritis and is considered safer than other immunosuppressive drugs. Reports on severe complications related to MMF are sparse. We report a case of a patient with lupus nephritis in whom severe complications were possibly caused by MMF. The patient was a 17-year-old girl who received a diagnosis of lupus nephritis at the age of 14 years and had been taking steroid and immunosuppressive agents since then. One week after starting MMF 1 g/day instead of mizoribine owing to symptom relapse and serologic data deterioration, she presented with seizure, accompanied by leukopenia, thrombocytopenia, and renal failure. We discontinued MMF because she had extremely high serum mycophenolate acid concentration (88 µg/mL). A few weeks later, she recovered without any complications and was discharged. Although rare, clinicians should be aware that serum mycophenolate acid concentration may become extremely high in the setting of acute kidney injury. In such circumstances, they should perform serum concentration monitoring to avoid possible adverse events.