Presented by: Mark I Sultan MD
University of California, Irvine

Introduction

24-hour urine collections are obtained as part of the metabolic workup for nephrolithiasis to identify modifiable analyte abnormalities for stone prevention. We sought to discern trends in the prevalence of metabolic abnormalities based on age and gender.

Materials

All Litholink 24-hour urine collections for nephrolithiasis patients obtained at our institution between 2004 and 2020 were retrospectively reviewed. Only the first 24-hour urine collection prior to intervention for each patient was included in the analysis. Patients were grouped by age (<50, >50) and gender. Litholink’s gender specific reference ranges were used to define abnormalities. 

Results

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1477 patients were included. The mean age at collection was 56 years (53.5% male, 46.5% female). Table 1a shows the prevalence of each abnormality after stratification for age and gender. Table 1b shows the prevalence of the analyte abnormality and the significance in difference between demographic groups. Male patients (particularly older men), demonstrated higher rates of hyperoxaluria (OR=2.93 [2.34-3.68]), in addition to (in particularly younger men) hyperuricosuria (OR=2.55 [1.96-3.32]) and an elevated urine sodium (OR=2.33 [1.89-2.88]). Female patients, particularly younger stone formers, demonstrated an increased prevalence of low urine volume (OR=1.46 [1.16-1.83]) and hypercalciuria (OR= 1.73 [1.39-2.14]); meanwhile, older females demonstrated higher rates of hypocitraturia (OR=2.19 [1.78-2.70]). Older patients were more likely to have low urine pH (OR=2.37 [1.65-3.41]) compared to younger patients.

Conclusion

Metabolic risk factors for nephrolithiasis vary significantly between different genders and age groups. These variations can be attributed to hormonal factors, diet, and lifestyle habits.  These findings may demonstrate the importance of 24 h urine evaluation to tailor specific dietary intervention and directed medical therapy based on abnormalities. More studies are needed to better understand the complex pathogenesis of nephrolithiasis and its relation to gender and age. 

Funding

None

Lead Authors

Mark I Sultan, MD
University of California, Irvine

Co-Authors

Sohrab N Ali, MD FRCSC
University of California, Irvine

Pengbo Jiang, MD
University of California, Irvine

Roshan M Patel, MD
University of California, Irvine

Ramy Youssef, MD
University of California, Irvine