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J Am Coll Surg. 2018 Aug;227(2):232-237. doi: 10.1016/j.jamcollsurg.2018.04.033. Epub 2018 May 26.

Does Urinary Bisphenol-A Change after Bariatric Surgery?

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Department of Surgery, Stanford University School of Medicine, Stanford, CA.
Department of Urology, University of California, San Francisco, San Francisco, CA.
Department of Surgery, Stanford University School of Medicine, Stanford, CA. Electronic address:



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.

[Indexed for MEDLINE]

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