Does Bariatric Surgery Also Improve Thyroid Function?

TOPLINE:

Metabolic/bariatric surgery (MBS) reduces thyroid-stimulating hormone (TSH), free triiodothyronine (fT3) levels, and thyroid hormone resistance indices in patients with obesity, changes strongly correlated with improvement in body composition. 

METHODOLOGY:

• Recent studies have linked obesity with increased levels of TSH and thyroid hormones; however, the role that body fat distribution plays in this association remains unclear.
• This retrospective observational study evaluated the effects of MBS on thyroid hormone levels and thyroid hormone resistance in euthyroid individuals with obesity, focusing on the correlation with changes in body composition.
• Researchers included 470 patients with obesity (mean age, 33.4 years; mean body mass index [BMI], 37.9; 63.2% women) and 118 control individuals without obesity (mean BMI, 21.8), who had had normal levels of TSH, fT3, and free thyroxine.
• Among the patients with obesity, 125 underwent MBS and had thyroid tests both before and ≥ 3 months after surgery.
• Data on body composition and thyroid function were collected, and correlations between baseline and changes in thyroid function and body composition were assessed.

TAKEAWAY:

• Individuals with obesity had higher baseline TSH and fT3 levels (P < .001) and thyroid feedback quantile-based index (TFQI; P = .047) than those without obesity, with the values decreasing after MBS (all P < .001).
• Among individuals with obesity, preoperative TSH was positively correlated with the visceral fat area (VFA; P = .019) and body fat percentage (P = .013) and negatively correlated with skeletal muscle mass percentage (P = .024)
• The decrease in TSH post-surgery positively correlated with decreased VFA (P = .021) and decreased body fat percentage (P = .031).
• Decrease in VFA and body fat percentage after MBS was also associated with improved central thyroid hormone resistance indicated by TFQI.

IN PRACTICE:

“The relationship between obesity and [thyroid hormone] is bidirectional, indicating that addressing underlying thyroid disturbance could potentially benefit weight loss and metabolism,” the authors wrote.

SOURCE:

This study was led by Yu Yan, MD, Department of Pancreatic and Metabolic Surgery, Medical School of Southeast University, Nanjing Drum Tower Hospital, Nanjing, China, and published online in The Journal of Clinical Endocrinology & Metabolism.

LIMITATIONS:

The retrospective nature of this study limited the ability to definitively attribute changes in thyroid function and thyroid hormone resistance to changes in body composition. The relatively short duration of the study and the exclusion of individuals taking medications affecting thyroid function may also limit the generalizability of the findings.

DISCLOSURES:

This study was supported by the Fundings for Clinical Trials from the Affiliated Drum Tower Hospital, Nanjing University Medical School, Nanjing, China. The authors declared no potential conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.