It is now clear that the coronavirus disease 2019 (COVID-19) pandemic is a challenging and long-standing healthcare problem rather than a temporary condition . Iran is one of the countries severely affected by the COVID-19 pandemic . The COVID-19 pandemic influences different aspects of human beings’ lifestyle and health. Most of the healthcare resources are focused on COVID-19 globally . The COVID-19 outbreak could increase stress among all population groups, with certain groups, such as patients with chronic diseases, at higher risk . Social limitations have adverse effects on mental health, physical activity, and dietary habits . All of these changes could impair the care of patients with chronic diseases .
Kidney stone disease has a high prevalence, incidence, and recurrence rate in the recent decade [5, 6]. Because the disease and its recurrence cause a high burden , prevention is of utmost importance in this condition . The main target of preventive recommendations is to modify dietary habits and reduce lifestyle risk factors . In patients with a high risk of recurrence, an extensive metabolic workup is recommended to identify stone risk factors and initiate a specific diet and medical treatments for each patient. Generally, kidney stone patients are recommended to have high fluid, high fruit and vegetable, restricted sodium, and adequate calcium intake. Besides, all patients should be encouraged to have adequate physical activity and keep a normal weight .
Such as other chronic diseases, the treatment and prevention of kidney stones have markedly changed during the COVID-19 pandemic . The European Association of Urology (EAU) considered metabolic evaluation a low priority action during COVID-19 . The panel recommended that stone analysis should be performed in first-time stone formers using a valid procedure, and extensive metabolic evaluation should be postponed. However, it is noteworthy that this recommendation should not diminish the importance of kidney stone prevention since low compliance with stone prevention recommendations might lead to stone recurrence, renal colic, urologic emergencies, and kidney injuries. Furthermore, the dietary and lifestyle changes caused by pandemics may independently be the risk factors for kidney stone formation. Therefore, we must balance the risk of kidney injures or emergent urologic interventions due to postponing stone clinic visits against the risk of COVID-19 exposure because of stone clinic appointments.
Some of the dietary habit changes during the COVID-19 outbreak may be risk factors for kidney stone formation. The stress-caused overeating and carbohydrate craving  increase the risk of developing obesity. Moreover, studies showed a decreased intake of vegetables and some types of fruit  and increased consumption of processed foods, high in fat, sugar, and salt [11,12,13]. All of these changes could increase the risk of stone recurrence. However, data regarding the dietary changes during pandemics is limited and controversial.
According to the studies, some of the 24-h urine (24-U) metabolites reflect patients' diet and can be used as a surrogate for their dietary intake. These metabolites include urine volume (primary determinant of fluid intake), urea (a marker of total protein intake), uric acid (could be used as a marker of animal protein), magnesium (reflecting the intake of whole grains, legumes, and nuts), and potassium (reflecting the intake of vegetables and fruits) [14,15,16,17].
In the current study, we compared the 24-U metabolites of patients during and before COVID-19 pandemics to investigate the dietary changes during the COVID-19 era in our stone prevention clinic in Tehran, Iran.