title: The effect of dietary protein on cystine excretion in patients with cystinuria.
abstract: Seven patients with homozygous cystinuria were studied on a metabolic ward to determine the effect of dietary manipulation on urinary cystine excretion. Isocaloric diets were calculated based on body weight and activity. Balance studies were performed for 5 days on a low protein diet (9.4 +/- 1.0% total calories) with equal amounts of animal and plant protein sources and an additional 5 days on a high protein (27 +/- 3.0% of total calories) with 70% animal protein. A significant (p less than 0.01) decrease in the excretion of 1/2-cystine, histidine, 3-methylhistidine, 1-methylhistidine, lysine, and ornithine plus arginine occurred on the low protein diet. The mean excretion of 1/2-cystine on the high protein diet was 6.13 +/- 1.48 mMoles per 24 hours which decreased to 4.89 +/- 1.06 mMoles per 24 hours on the low protein diet (p less than 0.001). Thirty seven percent of urine collections during the study were less than 2 liters/24 hours despite the fact that patients were encouraged to drink enough fluid to make 3 liters of urine/24 hours. For patients whose customary diet is high in animal protein, a more vegetarian diet may significantly reduce urinary cystine excretion. Cystine excretion in patients with cystinuria may be significantly different from day to day if animal protein consumption is variable.
mesh_terms: D000293:Adolescent; D000328:Adult; D001835:Body Weight; D003555:Cystinuria / Q000178:diet therapy / Q000652:urine*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000627:therapeutic use*; D002149:Energy Intake; D005260:Female; D006639:Histidine / Q000652:urine; D006801:Humans; D007669:Kidney Calculi / Q000178:diet therapy; D008239:Lysine / Q000652:urine; D008297:Male; D008762:Methylhistidines / Q000652:urine; D009952:Ornithine / Q000652:urine; D013997:Time Factors
chemical_list: D004044:Dietary Proteins; D008762:Methylhistidines; D006639:Histidine; D009952:Ornithine; D008239:Lysine