Does Urinary Bisphenol-A Change after Bariatric Surgery?

Abstract

One of the world's highest volume chemicals is bisphenol-A (BPA), an organic compound with a high solubility in fat. An emerging body of literature has suggested a link between BPA, obesity, and insulin resistance. The study aim was to determine if surgical weight loss is associated with changes in BPA levels. Demographic, preoperative, and 3-, 6-, and 12-month postoperative urine and laboratory data were prospectively collected on 22 bariatric surgery patients at a single academic institution. Laboratory values included hemoglobin A1C, fasting insulin, and fasting glucose. Demographic, preoperative and postoperative data, and urinary BPA levels were compared using Student's t-tests and simple regression analyses using GraphPad Prisim6 software. Patients were predominantly privately insured (86%), female (83%), and white (68%). Urinary BPA excretion was negatively correlated with weight at 6 months (r = -0.47, p = 0.029) and 12 months (r = -0.65, p = 0.006). The average weight before surgery was 274 pounds. Average preoperative BPA excretion was 2.4 ng/mL (SD = 1.0 ng/mL) in patients lighter than average weight and 1.3 ng/mL (SD = 0.7 ng/mL) in patients heavier than average weight (p = 0.006). Average BPA excretion at 12 months was 2.5 ng/mL (SD = 2.2 ng/mL) among lighter patients and 0.58 ng/mL (SD = 0.4 ng/mL) among heavier patients (p = 0.05). Follow-up included 18 patients at 3 months, 22 patients at 6 months, and 16 patients at 12 months. Higher urinary excretion of BPA preoperatively correlated with lower 6-month patient weight (r = -0.557, p = 0.025). Higher preoperative fasting insulin correlated significantly with reduced BPA excretion at 6 months postoperatively (r = -0.5366, p = 0.032). Excretion of BPA increases as bariatric surgery patients lose weight. Heavier patients with insulin resistance may store more BPA in adipose tissue and therefore excrete less BPA.