Objective. The purpose of this study was to induce nephrocalcinosis (NC) in rabbits with phosphate, vitamin D, oxalate and furosemide, to determine the effect on renal function and to correlate detection on ultrasound (US) and computed tomography (CT) with pathology. Materials and methods. Seventy-five immature New Zealand white rabbits were divided into five groups of 15. In each group, 5 animals were controls and 10 were given oral phosphate, furosemide, vitamin D or oxalate. Unilateral nephrectomy was performed at 3-6 weeks, and 5 rabbits of each test group were withdrawn from the substance. Weekly US was performed as well as US, CT and measurement of serum creatinine at the time of nephrectomy and prior to planned demise. Results. A total of 140 kidneys in 75 rabbits had both pathological and US correlation, with CT correlation in 126. Forty rabbits developed nephrocalcinosis with early (post nephrectomy at 3-6 weeks) or late (post demise at 12-20 weeks) pathological correlation obtained in 53 kidneys. Forty-one of these kidneys were from test animals: 23 developed NC early, 18 late. Twelve controls developed NC: 4 early, 8 late. Comparing US and CT to pathology, the sensitivity was 96% for US, 64% for CT. Specificity was 85% for US and 96% for CT. In 109 kidneys, information on serum creatinine level was available to correlate with pathology. The mean creatinine level was 138 mmol/l for those with NC and 118 mmol/l for those without NC (P<0.001). Conclusion. In this study, the presence of NC was significantly associated with increasing serum creatinine. Overall, US was more sensitive and CT was more specific in the detection of NC.

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 Unilateral nephrectomy was performed at 3-6 weeks, and 10 of the test group were withdrawn from the substance.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.