Acute tacrolimus nephrotoxicity in kidney transplanted patients - from kidney biopsy to urinary markers of acute kidney injury: a case report

Calcineurin inhibitors (CNIs) play a major role in kidney transplant immunosuppressive regimens, but they also may cause acute and chronic kidney toxicity, which is an important cause of long-term graft failure if not recognized and treated promptly. Therapeutic approaches are different and sometimes even opposite in acute graft dysfunction, requiring detailed differential diagnosis. Current guidelines consider the renal biopsy to have the highest specificity and sensitivity in the diagnosis and correct therapy guidance of acute graft dysfunction. However, the renal biopsy is an invasive and expensive method that predisposes to complications. In the last decade, a number of studies were focused on the urinary levels of various biomarkers like kidney injury molecule-1 (KIM-1), neutrophil gelatinase associated lipocalin (NGAL), interferon induced protein-10 (IP-10) or cystatin C (CysC) as potentially valuable non-invasive methods of allograft pathology diagnosis. We report the case of a 27 year-old male who underwent a kidney transplant and for which the urinary measurement of these biomarkers proved extremely useful in diagnosing the acute tacrolimus nephrotoxicity, which further allowed a correct therapeutic approach.