Effect of dietary phosphorus restriction on the kidneys of cats with reduced renal mass

SUMMARY Cats with reduced renal mass were fed a phosphorus-restricted diet (0.42% P, dry weight) or a normal phosphorus diet (1.56% P, dry weight) for 65 to 343 days. Renal function was determined biweekly by blood urea nitrogen and plasma creatinine measurements and by initial and terminal inulin clearance procedures. Neither diet caused a significant change in renal function during the study. However, histologic examination of kidneys obtained at necropsy clearly separated the cats on the basis of dietary phosphorus. The kidneys from cats fed the normal phosphorus diet had mineralization, fibrosis, and mononuclear cell infiltration, whereas the kidneys from cats fed the phosphorus-restricted diet had little or no changes.