Infrequent tacrolimus-induced nephrotoxicity in French patients with steroid-dependent nephrotic syndrome

Background Chronic nephrotoxicity with potentially irreversible lesions is a major concern regarding calcineurin inhibitor (CNI) treatment in children with severe forms of idiopathic nephrotic syndrome (INS). Case-diagnosis/Treatment We retrospectively included all children on CNI for steroid-dependent INS with a duration of CNI treatment of more than 1 year. Only patients in whom CNI could not be replaced by mycophenolate mofetil were included. All included patients underwent a kidney biopsy. All results were expressed as median and range. Twenty-one children (6 girls) were included. Age at disease onset was 49 (29–66) months and treatment duration on CNI was 30 (20–45) months. Age at kidney biopsy was 108 (78–170) months. Number of relapses was 7 (3–9) since disease onset. Serum creatinine level was transiently and moderately increased in two patients. Kidney biopsy revealed minimal change disease in 20/21 patients and focal segmental glomerulosclerosis in 1/21. Evidence for chronic CNI nephrotoxicity was found in one patient revealed by arteriolar hyalinosis and fibrosis in 50% of glomeruli. Conclusions CNI-induced chronic nephrotoxicity was infrequent. In patients who require long-term and/or high-dose CNI treatment, kidney biopsies might be useful to exclude chronic CNI-induced lesions.