#3626 A CASE OF PODOCYTE DISEASE WITH AZOTEMIA FOLLOWING TREATMENT WITH INTRAVENOUS IBANDRONATE

Abstract Background and Aims Bisphosphonate use may induce several types of nephrotoxicity. There are many reports on pamidronate-associated glomerular disease, such as focal segmental glomerulosclerosis and zoledronate-associated acute tubular necrosis. However, there are limited reports on ibandronate-associated nephrotoxicity. Herein, we describe a case of podocyte disease accompanied with azotemia following intravenous administration of ibandronate. Method Case report Results An 88-year-old female was referred to the emergency room due to grade 4 edema that developed 1 month before. The patient was diagnosed with osteoporosis 20 months earlier, for which she received quarterly intravenous administration of ibandronate (3 mg). The last dose was administered 2 weeks ago. The patient had no history of diabetes, hypertension, or chronic kidney disease. Laboratory tests revealed heavy proteinuria with a protein/creatinine ratio (PCR) of 32 and hypoalbuminemia (1.9 g/dL) with elevated serum creatinine (sCr) (1.8 mg/dL). Values of serum complement and electrophoresis were within normal ranges. The renal ultrasonogram was unremarkable. A renal biopsy was performed and light microscopy showed mild mesangial hypercellularity and segmental amorphous collagenous deposition in the glomerulus (Fig. 1-A). The tubules revealed focal marked atrophy and interstitial fibrosis (Fig. 1-B). Immunofluorescence studies were unremarkable. Electron microscopy showed diffuse effacement of foot processes and no electron-dense deposit (Fig. 1-C), consistent with podocyte disease favoring focal segmental glomerulosclerosis. The patient was treated with tacrolimus and fimasartan. Steroid use was spared owing to severe osteoporosis. Three months later, the edema subsided and laboratory findings improved (PCR 0.64, serum albumin 4 g/dL, sCr 1.23 mg/dL). Conclusion Compared to pamidronate and zoledronate, ibandronate is more highly protein-bound with a significantly shorter renal tissue half life, which might explain the rarity of ibandronate-related nephrotoxicity. Contrary to the trend of other bisphosphonates nephropathies, our case showed simultaneous podocyte disease and tubule damage. We recommend close monitoring of proteinuria and renal function for prompt nephrotoxicity detection in patients treated with ibandronate.