Presented by: T. Max Shelton MD
Indiana University School of Medicine

Introduction

Nephrolithiasis is a common medical issue affecting an estimated 1 in 11 people in the United States. Inadequate fluid intake has been shown to play a role in stone development. There is a lack of consensus regarding seasonal variations in urine volumes and little published on seasonal variations in urine electrolytes. This study evaluates seasonal variations in 24-hour urine parameters among a large cohort of stone-formers at a single institution.

Materials

Data from 2,779 24-hour urine tests from 2017-2022 was used to calculate seasonal averages for urine testing variables. Subsequently, an ANOVA single factor test was used to determine the statistical significance of the results using a p-value of 0.05.

Results

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Urine volumes, urine chemistries and super-saturations were analyzed for a total of 2,779 24-hour urine studies. Urine sodium and chloride were statistically lower during summer months (June-August) at 154.6 vs. 170.5 mmol/d (p= 0.00003) and 157.2 vs. 170.4 mmol/d (p=0.0008). This seasonal variation was also reflected with urine urea nitrogen (p=0.0346), magnesium (p=0.0357), and phosphorus (p=0.0266). The remainder of analyzed factors showed no statistically significant difference.

Conclusion

This study shows statistically significant decreases in urine sodium, chloride, magnesium, and phosphorus during the summer season compared to other yearly averages. The decreases in these parameters may be due to electrolyte losses from perspiration, although other dietary factors warrant study. Interestingly, no significant seasonal variations were noted in urine volumes, super-saturations, or other urine electrolytes.

Funding

None

Co-Authors

Najash Abdishkur,
Indiana University School of Medicine

Joel Green,
Indiana University School of Medicine

Luke Vandeventer,
Indiana University School of Medicine

RJ Caras, DO
Indiana University School of Medicine

Austen Slade, MD
Indiana University School of Medicine

Marcelino Rivera, MD
Indiana University School of Medicine