Presentation Authors: Manuel Armas-Phan*, David Bayne, Scott Wiener, Tim Liang, Jeremy Goodman, Marshall Stoller, Tom Chi, San Francisco, CA
Introduction: Cystinurics suffer from impaired reabsorption of dibasic amino acids & recurrent calculi with lengthy periods of quiescence interrupted by periods with multiple frequent symptomatic stone episodes. How diet impacts these two different time periods remains unclear. Literature suggests protein, methionine, & sodium consumption can alter quantitative urinary cystine levels. This study aimed to determine the impact of dietary input associated with symptomatic stones in need of surgery.
Methods: Cystinuric patients were recruited for a food frequency & activity questionnaire (NutritionQuest) from an ongoing single site randomized control trial evaluating a novel medical intervention for cystinuria. All patients enrolled in the trial were contacted & respondents were divided into two groups defined as those who had undergone stone surgery within the last 2 years or not. Differences were compared using Wilcoxon rank-sum & Fisher&[prime]s exact tests on Stata v15.1.
Results: 15 patients completed the questionnaire, of whom 6 had undergone stone surgery within 2 years of study enrollment. There were no differences between the groups with respect to age, gender, race, education, or BMI. 6 patients reported recent symptoms, 4 of which culminated in recent stone surgery. There were no differences in caloric, carbohydrate, & fat intake. Those who had recently undergone stone surgery consumed more daily protein (65.9g v. 50.7g), cysteine precursors (serine & methionine: 3.0g v 2.4g & 1.5 v 1.1g, respectively), & cysteine (0.9g v 0.7g) but these differences were not statistically significant (P < 0.10). Cystinurics with recent stone surgery consumed more sodium (3.2g v 2.2g) (p < 0.05) & had an increased oxalic acid consumption (230mg v. 150mg) (p < 0.01). There were no differences in water intake (2.4L v. 2.2L).
Conclusions: To the best of our knowledge, this is the first attempt to assess diet&[prime]s role in culminating in symptomatic cystine stone disease requiring surgical intervention. Interestingly, cystinurics who recently experienced stone surgery consumed more protein, minerals, & oxalic acid suggesting that consumption of these dietary components may tip cystinuric patients from quiescent periods to times where surgery is required. Future investigations utilizing this questionnaire will be performed to refine relationships between dietary inputs & cystinuric outcomes.
Source of Funding: NIH P20-DK-100863, P20-DK-116193, R01-FD-005716, NIH TL1-TR-001871, & Urology Care Foundation Medical Student Fellowship