Effects of Uninephrectomy on Calcium Oxalate Nephrolithiasis in Ethylene Glycol-Treated Rats

Moon, Young Tae; Ahn, Seung Hyun; Lee, Yong Seong; Shin, Ji Hyun

Abstract

PURPOSE: A renal compensatory hyperfunction after the surgical removal of a contralateral normal kidney includes hyperfiltration and hyperexcretion. These changes in the remaining kidney may increase or decrease the stone-forming potential. The effects of a uninephrectomy (uNX) on stone formation were investigated in an animal model.
MATERIALS AND METHODS
Adult male Sprague-Dawley rats (300-350gm) were divided into 3 groups (n=10 in each). Group 1 were left untreated and served as the control. Group 2 were fed 0.8% ethylene glycol and 1% ammonium chloride (crystal-inducing diet, CID) in their drinking water for 4 weeks without a uNX. Group 3 were fed the same CID for 4 weeks from 2 weeks after the uNX. The stone metabolic study analyzed the excretion rate differences of the lithogenic and inhibitory constituents in the serum and 24-hour urine in the rats. The crystal deposits were examined by polarizing microscopy and the renal calcium content was measured by atomic absorption spectroscopy.
RESULTS
There was a significant difference between the control group (56.44+/-4.90 ng/gm) and the CID-treated groups in terms of the renal calcium content (p< 0.01). In addition, the magnitude of the increase was significantly higher in group 3 (2875.50+/-1783.90 ng/gm) than in group 2 (1053.54+/-866.71ng/gm) (p< 0.05). The mean grade of the crystal deposit in group 3 (3.60 +/- 0.70) was markedly higher than in group 2 (2.40 +/- 1.35) (p< 0.05). When comparing group 2 and 3, the serum creatinine level increased significantly (p< 0.05), whereas the creatinine clearance and 24-hour urinary excretion of citrate decreased significantly (p< 0.05).
CONCLUSIONS
The results suggest that uNX increases the stone-forming potential of the remaining kidney in the presence of other lithogenic risk factors.