[Bisphosphonate-induced collapsing focal segmental glomerulosclerosis; two clinical cases and literature review]

Collapsing focal segmental glomerulosclerosis is well described in its idiopathic form, mostly seen in young African American patients, and in association with HIV virus. Its clinical presentation typically includes proteinuria and renal failure rapidly progressing to end stage renal disease. However, a new form has recently been described related to treatment with high doses of intravenous bisphosphonates, especially pamidronate. We report two cases of collapsing focal segmental glomerulosclerosis in patients treated with intravenous pamidronate. In opposition to previous reports, interruption of pamidronate administration did not improve renal function. The latter should be evaluated before initiating treatment with bisphosphonates and regularly monitored. For patients with chronic kidney disease, introduction of bisphosphonates should be reconsidered given the risk of rapid progression to end stage renal disease and the lack of evidence for reduction of fracture risk in this population.