Metabolic diagnoses of recurrent stone formers: temporal, geographic and gender differences.

Background: Metabolic factors underlying the recent increase in stone prevalence over the past decades are not well understood. Herein, we evaluate temporal, geographic and gender-specific trends in metabolic risk factors in recurrent kidney stone formers.

Patients And Methods: A systematic literature review of metabolic risk factors for stone formation was conducted, inclusive of the last four decades. Studies with inadequate 24 h urine metabolic data, pediatric or those with less than 50 patients were excluded. The primary outcome was prevalence of each metabolic risk factor, compared between studies published prior to the year 2000 vs those following. Geographic and gender differences were secondary outcomes.

Results: Twenty-eight articles met inclusion criteria, of which 10 ( = 1578) were published prior to the year 2000 and 18 ( = 8747) were published thereafter. Comparing these groups, an increase in hyperoxaluria (29% vs 33%;  = 0.002), hypercalciuria (35 vs 36%;  = 0.446), hyperuricosuria (17% vs 22%;  < 0.0001), low urine volume (28 vs 38%;  < 0.0001) and hypocitraturia (23% vs 44%;  < 0.0001) was observed. The prevalence of hyperoxaluria, hypercalciuria, hyperuricosuria and hypocitraturia were significantly higher in males. There were also significant geographical differences, with higher prevalence of hyperoxaluria and hypocitraturia in non-Western countries and higher prevalence of hypercalciuria in Western countries. Prevalence of hyperoxaluria is increasing in the US.

Conclusion: Prevalence of metabolic risk factors for nephrolithiasis significantly increased in recent years. These findings are hypothesis-generating and may provide valuable insight into the epidemiology, prevention and management of recurrent stone disease. Dietary modifications and innovative medical therapies are needed to decrease metabolic risk factors underlying nephrolithiasis.