Introduction: In New York State, March 16, 2020 marked the end of any in-restaurant dining due to the COVID-19 pandemic. The general population was forced to do more cooking at home and less dining out. Dietary modifications like this are considered first line therapy for calcium stone formers due to an effort to reduce dietary sodium intake which is known to affect lithogenic risk factors including hypernatriuria and hypercalciuria. This study aims to see if dietary changes made during the pandemic changed the risk of stone disease as evidenced in 24-hour urine studies and if these changes ceased after the end of widespread shutdowns. Methods: All patients with nephrolithiasis seen for an outpatient visit from April 1, 2020-December 31, 2020 were queried and included if they had a 24-hour urine study pre-COVID (before March 16, 2020) and during-COVID (March 16, 2020-December 31, 2020); a post-COVID study was included if available (January 1, 2021- October 31, 2022). Values were compared using paired, 2-tailed t-tests. Results: 93 patients (54 males, 39 females, mean age 60.1) were studied pre-COVID, during-COVID, and post-COVID time periods with 24-hour urine studies. Stone analysis revealed calcium oxalate (61%), calcium phosphate (15%), uric acid (15%), other (9%). The 24-hour urine revealed a significant reduction in urinary sodium (uNa) and urinary calcium (uCa) in these patients. uNa levels decreased from 166.15 ± 7.5 mEq/L pre-COVID to 149.09 ± 7.6 mEq/L during-COVID (p=0.015) and maintained improved at 138.55 ± 6.83 mEq/L post-COVID era (p=0.0035). uCa levels decreased from 214.18 ± 13.05 mEq/L pre-COVID to 191.48 ± 13.03 mEq/L during-COVID levels (p=0.010) and remained improved at 185.33 ± 12.61 mEq/L post-COVID (p=0.012). There were no significant differences in 24-hour urine total volume, magnesium, or citrate levels. Conclusions: During the COVID-19 lockdown, dietary choices limited to home cooked meals allowed patients to better identify their food choices. This study demonstrates that known urinary risk factors for lithogenesis, such as urinary sodium and calcium, improved during the lockdown and these improvements were maintained even after restrictions in restaurants were lifted. Moving forward, it will be imperative to monitor patient’s 24-hour urine to ensure these dietary modifications are continued in the post-pandemic era and to see if these improved urinary parameters will impact stone formation in these patients. SOURCE OF Funding: None
