Pattern and permanence of phosphate-induced nephrocalcinosis in rabbits

Objective. The purpose of this study was to observe the pattern and permanence of phosphate-induced nephrocalcinosis (NC) in rabbits. Materials and methods. Thirty immature New Zealand white rabbits were divided into 10 controls and 20 test subjects who were given oral phosphate. Unilateral nephrectomy was performed at 3-6 weeks, and 10 of the test group were withdrawn from the substance. All surviving rabbits were terminated at 6-14 weeks post nephrectomy. Weekly US was performed, as well as US, CT and serum creatinine evaluation at the time of nephrectomy and prior to planned demise. Results. Of the 20 rabbits that received oral phosphate, 16 had NC by 3 weeks and the remainder by 6 weeks. The severity was proportional to intake. NC occurred in the cortex in 69%, the corticomedullary junction (CMJ) in 81% and the medulla in 27% of cases. Only 5 of 10 rabbits that returned to oral water post nephrectomy were suitable for follow-up on pathology. NC improved in 3 of these animals. Conclusion. NC in rabbits occurs maximally at the CMJ but also frequently in the cortex. NC was not permanent or static but improved in 3 of 5 rabbits when phosphate was withdrawn.