Open Access

ARTICLE

Visceral adipose tissue loss and 24-hour urinary profile changes post-bariatric surgery

Michael Uy¹, Richard Di Lena¹, Jen Hoogenes^1,2, Badr Al-Harbi³, Aidan Woodward⁴, Bobby Shayegan^1,2, Edward D. Matsumoto^1,2

1 Department of Surgery, Division of Urology, McMaster University, Hamilton, Ontario, Canada
2 St. Joseph’s Healthcare Hamilton, Hamilton, Ontario, Canada
3 Department of Surgery, College of Medicine, Qassim University, Buraydah, Saudi Arabia
4 School of Medical Science, Faculty of Science and the Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
Address correspondence to Dr. Edward D. Matsumoto, St. Joseph’s Healthcare Hamilton, McMaster Institute of Urology, 50 Charlton Avenue East, G-343, Hamilton, ON L8N 4A6 Canada

Canadian Journal of Urology 2022, 29(1), 11005-11011.

Abstract

Introduction: The relationship between obesity and nephrolithiasis is a well-documented phenomenon. Visceral adipose tissue (VAT) has been proposed to be an accurate indicator of metabolic derangement. We present a study that investigates the relationship between computed tomography (CT) delineated VAT measurements and 24-hour urine (24 HU) profiles in the context of profound weight loss.
Materials and methods: A total of 86 patients with a history of nephrolithiasis who underwent bariatric surgery were reviewed. All patients had pre and postoperative 24 HU analysis and CT kidney and urinary bladder performed. CT-based fat delineation program, AnalyzePro, was used to measure VAT at levels L4-L5 (VAT 1) and L1-L2 (VAT2). Univariate and multivariate analysis was utilized to examine associations between VAT measurements and comorbidities, 24 HU values, and postoperative urinary changes.
Results: Preoperative VAT2 was correlated with preoperative serum creatinine and all 24 HU (R2: 0.23-0.43, p = < 0.001-0.030). Only VAT1 and VAT2 had relationships with hypertension, dyslipidemia, and metabolic syndrome (R2: 0.25-0.30, p = 0.004-0.015). The percent change in VAT1 and VAT2 was a significant predictor of change in 24 HU uric acid (respectively, R2: 0.14, beta: -0.03, p = 0.002 and R2: 0.13, beta: -0.03, p = 0.003).
Conclusions: This study found VAT to have strong correlations with urinary outcomes in obese patients, especially in the excretion of uric acid. These findings support a potential use of CT delineated measurements of fat as a surrogate measure for urinary metabolites, and may be used as a marker for patient counseling in stone prevention.

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