Objective The aim of the present study was to evaluate the impact of body mass index (BMI) on urinary excretion of different metabolites in patients with nephrolithiasis. Methods A systematic search of PubMed and Scopus was performed up to July 2019. The eligible studies based on inclusion/exclusion criteria were screened and their data were extracted. Finally, 91 articles were included for dose response analysis, of which, 14 articles were included. Patients were dichotomized according to their BMI, i.e. normal weight patients with BMI˂25 and overweight/obese patients with BMI≥25 kg/m². Results Our results indicated that normal weight stone forming patients excreted less calcium (p<0.001), uric acid (p<0.001), oxalate (p<0.001), sodium p<0.001), citrate (p<0.001) and magnesium (p<0.001), however, these patients also had a higher urinary pH (p<0.001). There was a linear dose-response relationship between BMI and 24-h excretion of oxalate (p linearity˂0.001), uric acid (p linearity ˂ 0.001), sodium (p linearity= 0.002), phosphate (p linearity = 0.006), citrate (p linearity = 0.003) and creatinine (p linearity=0.0006), respectively. Conclusion The findings from the present study highlight overweight and obesity increase the urinary excretion of both stone promoters (calcium, sodium, oxalate and uric acid) and inhibitors (citrate and magnesium) urinary pH and prevalence of kidney stones is still higher in overweight/obese patients. Overall, overweight and obese people have more chance to form the kidney stones.
Taheri, F., Djafarian, K., Clark, C., Taheri, M., Djafari, F., Honarkar-Shafie, E., ... Shab-Bidar, S. (2020). The association of body mass index and quantitative 24-h urine metabolites in patients with Nephrolithiasis: a systematic review and dose-response meta-analysis. Obesity Medicine, (In-Press), (In-Press). https://doi.org/10.1016/j.obmed.2020.100262