Is the ‘‘Pandemic Diet’’ Nonlithogenic?

Introduction and Objective: The COVID-19 pandemic and worldwide quarantine resulted in major changes in individual lifestyles. In New York State, March 16, 2020, marked the end of in-restaurant dining and a reported shift to more cooking at home. We investigated the 24-hour urine of patients with known history of nephrolithiasis to see if changes during COVID-19 pandemic altered the risk of stone disease. Methods: Retrospectively, patients with history of nephrolithiasis seen for an outpatient visit from April 1, 2020, to December 31, 2020, were studied. All patients had a 24-hour urine study ‘‘pre-COVID’’ defined as before March 16, 2020, ‘‘during-COVID’’ from March 16, 2020, to December 31, 2020; if available, ‘‘post-COVID’’ from January 1, 2021, to October 31, 2022, was also included. Mean study values were compared using paired, two-tailed t-tests. Results: Ninety-three patients (M = 54, F = 39) with a mean age of 60 years were evaluated. Twenty-four-hour urine revealed a significant reduction in urinary sodium (uNa) levels from pre-COVID (166.15 – 7.51 mEq/L) compared with during-COVID (149.09 – 7.55 mEq/L) (p = 0.015) and urinary calcium (uCa) levels from pre-COVID (214.18 – 13.05 mg) compared with during-COVID (191.48 – 13.03 mg) (p = 0.010). Post-COVID 24-hour urine (N = 73) levels for uNa (138.55 – 6.83 mEq/L, p = 0.0035) and uCa (185.33 – 12.61 mg, p = 0.012) remained significantly reduced compared with pre-COVID values, but with no difference compared with during-COVID values. Upon age stratification, this significance was found only in patients younger than 65. 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 home-cooked meals improved urinary parameters minimizing lithogenic risk factors for stone formation, including hypernatriuria and hypercalciuria. That these changes persisted into the post-COVID period may indicate improved dietary practices after the lockdown ended.