Diet calcium carbonate, phosphorus and acidifying and alkalizing salts as factors influencing silica urolithiasis in rats fed tetraethylorthosilicate

• Published in: The Journal of nutrition Vol. 116; no. 5; p. 823
• Main Authors: Schreier, C J, Emerick, R J
• Format: Journal Article
• Language: English
• Published: United States 01-05-1986
• Subjects: Administration, Oral; Animals; Bicarbonates - pharmacology; Body Weight; Calcium - blood; Calcium Carbonate - pharmacology; Carbonates - pharmacology; Diet; Drug Interactions; Hydrogen-Ion Concentration; Magnesium - blood; Male; Phosphorus - pharmacology; Phosphorus - therapeutic use; Rats; Rats, Inbred Strains; Silanes - metabolism; Silicon - metabolism; Silicon Dioxide - urine; Sodium - pharmacology; Sodium Bicarbonate; Urinary Calculi - chemically induced; Urinary Calculi - prevention & control
• ISSN: 0022-3166
• DOI: 10.1093/jn/116.5.823

Three experiments were conducted to determine the effects of excess dietary calcium carbonate, phosphorus and urine acidifying and alkalizing salts on silica urolith formation in a model using rats fed dextrose-based diets containing 2% tetraethylorthosilicate (TES). Diets containing 2% TES lowered weight gains to 91-95% of gains made by rats fed non-TES diets. Urine silica concentrations of rats fed TES were generally in the range of 50-60 mg/dl. In experiment 1, rats fed TES with no additional dietary calcium carbonate had a silica urolith incidence of 35%. With additions of 1 and 2% calcium carbonate to the basal-TES diet, respective urolith incidences were 45 and 60% (r = 0.99, P less than 0.02). In experiment 2, monobasic sodium phosphate (MP) providing 0.2% additional phosphorus resulted in a mean urine pH of 6.42 and no uroliths. Dibasic sodium phosphate (DP) without and with 0.5% sodium bicarbonate (SB) resulted in respective urine pH values of 6.78 and 7.14 and urolith incidences of 15 and 20% (MP less than DP and DP + SB, P less than 0.05). However, the uroliths were small averaging less than 1 mg. In experiment 3, substitution of autoclaved egg albumin for casein, the protein source in experiments 1 and 2, resulted in urine pH of 7.45 and a silica urolith incidence of 46%. An equal-molar mixture of MP and DP providing an added 0.2% phosphorus resulted in a urine pH of 7.07 and reduced the urolith incidence to 4%, and 0.75% of dietary ammonium chloride either with or without the added 0.2% phosphorus gave urine acidification and complete protection from uroliths.