Acute phosphate nephropathy.

PURPOSE OF REVIEW Acute phosphate nephropathy (APN) has been identified in renal biopsy specimens of patients exposed to oral sodium phosphate (OSP) bowel purgatives. Biopsy confirmed cases presented with bland urinary sediment, low-grade proteinuria, and varying degrees of creatinine elevation. Prospective identification of APN is difficult in that definitive diagnosis requires renal biopsy, and biopsy is rarely performed for patients with this clinical presentation. RECENT FINDINGS Observational studies evaluating acute kidney injury after OSP exposure using interval changes in creatinine as a surrogate for APN have reported conflicting results. Although these studies have produced estimates of disease occurrence, they have been unable to definitively quantify the overall risk of APN with OSP as compared with alternative bowel-cleansing agents. SUMMARY On the basis of association of APN and OSP, the US Food and Drug Administration issued a boxed warning and manufacturers have ceased production and distribution of some OSP products. As this is a temporary solution, more studies are needed to delineate the pathophysiology of this disease and to better identify the subset of the population at risk for APN.