Abstract
Background:
Studies evaluating changes in thyroid hormone replacement in hypothyroid patients following bariatric surgery have been inconsistent, reporting an increase, decrease, and no change in total thyroid hormone dose. We sought to evaluate this change and the factors that affect thyroid hormone dose following bariatric surgery in hypothyroid morbidly obese patients.
Methods:
We retrospectively analyzed 231 hypothyroid morbidly obese patients on levothyroxine replacement (LT4) who underwent Roux-en-Y gastric bypass, lap banding, or sleeve gastrectomy between January 2000 and December 2010. We analyzed for change in LT4 dose (actual and weight-based dose, μg/kg) and correlation between change in dose and confounding variables, including change in weight, body mass index (BMI), thyrotropin (TSH), vitamin B12, and 25 hydroxy vitamin D.
Results:
The prevalence of hypothyroidism in morbidly obese patients was 19% (231/1,221). Complete data were only available for 74/231 (32%) patients. LT4 requirements were variable in all surgical groups postoperatively. Overall, 19/74 (26%) had a decrease, 41/74 (55%) had no change, and 14/74 (19%) had an increase in actual LT4 dose. Median TSH (pre: 2.64 μIU/mL; post: 2.0 μIU/mL) and median LT4 dose pre- and postoperatively (125 μg for both) was not significantly different between groups. However, the weight-based LT4 dose following surgery was significantly increased postoperatively (pre: 0.95 μg/kg vs. post: 1.14 μg/kg; p≤0.01).
Conclusion:
Consistent with previous studies, total LT4 dose was variable following bariatric surgery, and there were no predictors of postoperative dose. All groups had an increase in weight-based LT4 dose following bariatric surgery, an observation that requires further study.
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