Combined Use of 30 % Lactose Rich Diet and 1 % Ethylene Glycol: A New Animal Model for Study of Urolithiasis

OBJECTIVE: We used a modified lithogenic diet by combining 30 % lactose and 1 % ethyl-ene glycol (EG) to improve the animal model for stone research. MATERIALS AND METHOD: Thirty male Sprague-Dawley adult rats weighing 250-300 gm were randomly divided into three groups. Each group consists of 10 rats. Group 1 served as control. Group 2 were fed with lactose rich diets (30%) and tap water for 4 weeks. Group 3 were fed with lactose rich diets and received 1 % EG in drinking water for 4 weeks. The crystalluria, stone and crystal deposits were examined by light and polarizing microscope, respectively. RESULT: There was no any urinary stone and crystal deposition in group 1 and 2 rats. The kidneys of group 3 rats were grossly enlarged and hydronephrotic. The size of urinary stones ranged from 2 to 5 mm in diameter (average 3.2 mm.). Stones were noted within the papillary tips in all Group 3 rats. CONCLUSIONS: The administration to rats of a diet containing 30 % lactose is an effective model for the study of calcium oxalate dihydrate crystalluria. Furthermore, the combination of 30 % lactose and 1 % ethylene glycol can effectively induce calcium oxalate stone formation and result in hydronephrosis. The present experimental model enables close simulation of the condi-tions in human and can be used for urinary stone research. (J Urol R.O.C., 11:149-54, 2000