Low Preoperative Free Triiodothyronine, Particularly in Females, Is Associated With Reduced Weight Loss and Diabetes Remission After Bariatric Surgery in Euthyroid Adults
In brief
Women with FT3 below 4.75 miss weight-loss and diabetes-remission goals after bariatric surgery
In a cohort of 1,034 euthyroid adults, pre-operative free triiodothyronine below 4.75 pmol/L in females (and 5.05 pmol/L in males) predicted a lower chance of losing at least 25% of weight and achieving diabetes remission over three years. The finding suggests sex-specific FT3 cut-offs could help select patients most likely to benefit, but prospective validation is needed.
- Journal
- Diabetes/metabolism research and reviews (Q1)
- Published
- 1 September 2026
- Study design
- Cross-sectional study
- Evidence level
- Level 3, Low (CEBM 3b)
- Authors
- Shaobo Li, Yinfang Tu, Hongwei Zhang, Yunfeng Xiao, Yuqian Bao, Jun Yin, et al.
- PMID
- 42733963
- DOI
- 10.1002/dmrr.70228
Why clinicians should know about it
- Picked for Bariatric and Metabolic Surgery (paper of the day, 15 September 2026): Ranked by evidence level and journal quartile
Abstract
AIMS: With the rising prominence of GLP-1 receptor agonists, identifying predictors of optimal bariatric surgery candidates has become increasingly important. We investigated cross-sectional relationships between thyroid hormones and obesity-related parameters, and evaluated the predictive value of baseline thyroid hormones for weight loss (WL) and diabetes remission (DR) after bariatric surgery. METHODS: This study included a cross-sectional cohort of 1567 euthyroid patients with overweight or obesity, of whom 1034 with complete 1 year postoperative data were included in the longitudinal analysis. Body composition was assessed using validated predictive equations and abdominal MRI. The primary outcomes were successful WL (total WL ≥ 25%) and DR (fasting glucose < 5.6 mmol/L and HbA1c < 6.0% without antidiabetic medications) during the 3 year follow-up. RESULTS: Breakpoint analysis indicated that free triiodothyronine (FT3) plateaued beyond an age threshold while showing a linear correlation with fat-free mass index. Higher baseline FT3 tertiles were significantly linked to increased likelihood of achieving successful WL and DR at 1 year follow-up, with stronger associations in females. Optimal FT3 thresholds were identified as 4.75 (females) and 5.05 (males) for WL, and 4.57 (females) and 5.00 (males) for DR. Preoperative FT3 levels below these thresholds were significantly associated with reduced WL and DR over 3 years. CONCLUSIONS: Serum FT3 exhibits an age-related breakpoint effect, and low preoperative FT3, particularly in females, is a critical predictor of suboptimal short- and long-term WL and DR success post-bariatric surgery. Sex-specific FT3 thresholds may aid in preoperative risk stratification and inform personalised treatment decisions in the era of expanding obesity therapeutics.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.