Hormones Causing Metabolic Abnormalities May Be Reduced By Gastric Bypass Surgery

Roux-en-Y gastric bypass (RYGB) surgery can reduce metabolic abnormalities caused by high levels of serum-free thyroxine (FT4) and thyroid-stimulating hormone (TSH) in euthyroid patients with obesity and type 2 diabetes, a recent study showed.

To better understand how bariatric surgery impacts thyroid hormone levels, the researchers assessed 81 euthyroid patients with obesity and type 2 diabetes who received RYGB surgery at a university hospital in China, as well as 20 healthy volunteers. The researchers measured changes in anthropometic paramaters, metabolic indexes, FT4, and TSH at baseline and 6 months post-surgery.
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Factors that could predict changes in FT4 and TSH were determined via multiple linear regression analysis.

Results showed that mean FT4 levels decreased from 16.26 pmol/L at baseline to 14.59 pmol/L at 6-month follow-up, whereas TSH levels decreased significantly at 6-month follow-up. The waist-to-hip ratio and duration of diabetes were both independent factors contributing to the decrease in FT4 levels, as shown by multiple linear regression analysis. Additionally, the researchers found that changes in TSH levels were significantly and positively correlated with 2-hour postprandial blood glucose at baseline.

“The present study is the first to show that both serum levels of FT4 and TSH decrease after RYGB in euthyroid patients with obesity and [type 2 diabetes mellitus],” the researchers concluded. “Our results suggest that not only can RYGB improve metabolic abnormalities, but it may also alter the feedback regulation of the thyroid system.”

—Christina Vogt

Reference:

Liu F, Di J, Yu H, Han J, Bao Y, Jia W. Effect of roux-en-Y gastric bypass on thyroid function in euthyroid patients with obesity and type 2 diabetes mellitus [Published online June 14, 2017]. Surg Obes Related Dis. doi:10.1016/j.soard.2017.06.001.