Publication:

Obesity and metabolic evaluation of 24 hour urinary analysis of adult stone formers, a case control study

Background Urinary tract stone (Urolithiasis) is a common problem nowadays. Frequencies of urolithiasis vary from region to region: 1-5% in Asia, 5-9% in Europe, 13% in North America. Urolithiasis is believed to be due to imbalance & crystallisation of minerals inside urine, which act as the focus for more sedimentation and finally the formation of a stone within the urinary tract. The comorbidities associated with urinary stones includes: renal colic, urinary tract infection, hydronephrosis, obstruction of the collecting system, renal parenchymal damage which ultimately leads to renal failure and even death. The aim of this study was to assess the relationship between obesity and the metabolic evaluation of 24 hour urinary analysis of stone formers.

Methods A case-control study was carried out on 70 patients aged ≥20 years with urolithiasis that were without any comorbidities treated between January 2014 to January 2015. We performed 24 hour urinary analysis on urolithiasis patients and classified them as being of low weight (body mass index; BMI: <18.5, 8 men, 5 women), normal weight (BMI: 18.5-24.9, 19 men, 7 women), overweight (BMI: 25-29.9, 30 men, 12 women) or obese (BMI≥30, 12 men, 7 women).140 healthy normal weight sex and age-matched controls were also included in the study in the ratio of 1:2.

Results There was a statistically significant difference in the prevalence of obesity between the urolithiasis group and the control group (p<0.05).The correlation analysis revealed a significant positive relationship between BMI and the serum calcium, uric acid, urinary calcium, uric acid and citrate, and there was an inverse relationship between BMI and urinary pH (p<0.05). The frequency of urinary stone risk factors was increased with BMI (p<0.05).

Conclusions The positive relationship between Obesity and the risk factors for urolithiasis was evident from this study. To understand the mechanism of urolithiasis in obese patient’s further research is required.