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Sources of Funding: AUA Research Scholar

Introduction

Greater body mass index (BMI) and type 2 diabetes mellitus are associated with kidney stone risk. Increased urinary excretion of oxalate (Uox) has been correlated to increasing BMI. Our objectives were to determine if this association is linked to hemoglobin A1C levels (A1C).

Methods

We retrospectively reviewed 1,428 twenty-four hour urine collections gathered from a single institution from 2004-2015 from two urologists. 665 unique non cystinuric adult stoneformers (SF) with complete data including BMI, age, gender, A1C levels, and Uox were then analyzed using ANOVA, Chi-squared, and linear regression analyses.

Results

Average age of SF was 49.9 years. 46% of SF were female. Average BMI was 29.2 (Underweight 1.4%, Normal weight 26.5%, Overweight 35.8%, Obese 27.7%, Morbidly Obese 8.6%). Greater BMI correlated with increased Uox (mg/d) (p≤0.0001, r=0.245) and remained significant for both males (p≤0.001, r=0.30) and females (p≤0.001, r=0.195). The positive correlation between BMI and Uox was also seen in both African American and Caucasian subjects (r=0.34, p=0.02 and r=0.20, p≤0.005). A significant positive correlation between A1C and Uox was demonstrated (r=0.24, p≤ 0.009).

Conclusions

Among SFs, there is a positive correlation between BMI and Uox as well as A1C and Uox. These relationships may explain associations between both obesity and diabetes and the development of kidney stones.

Funding

AUA Research Scholar