The performance of levothyroxine tablet is impaired by bariatric surgery

Abstract

Objective The aim was to evaluate if bariatric surgery can affect the LT4 performance. The endpoints were the following: 1) difference between LT4 daily dose before and 1 year after surgery, 2) difference between LT4 dose per weight before and 1 year after surgery, 3) difference among LT4 preparations. Methods The study period was between January 2018 and May 2022. Inclusion criteria were a) adults undergone bariatric surgery, b) with proven autoimmune hypothyroidism, c) on LT4 therapy before bariatric surgery, d) using any commercialized LT4 preparation. Excluded were patients a) proven to have or suspected for pre-surgical intestinal malabsorption, b) with other potential interfering factors on LT4 absorption; c) with heart, renal, and/or hepatic failure, d) with recent/current infection/inflammation, e) in pregnancy, f) with incomplete data about LT4 therapy. Results According to the selection criteria, 40 patients were included. Both TSH and LT4 daily doses were not significantly different with respect to baseline values. On the contrary, the LT4 dose per weight was significantly increased, especially in RYGB patients. An increased LT4 dose per weight was observed with the reduction of weight. Conclusion One year after bariatric surgery 1) the daily dose of LT4 remains unchanged, and 2) despite the significant weight reduction, LT4 dose per weight increases. Most data are referred to LT4 tablet and the performance of LT4 caps should be further investigated.

Obesity and Obesity-Related Thyroid Dysfunction: Any Potential Role for the Very Low-Calorie Ketogenic Diet (VLCKD)?

“…The dosage of L-T4 should be adapted based on the patient's BMI, lean body mass, age, sex, and other factors affecting L-T4 absorption and metabolism [79][80][81][82]. Moreover, considerations for L-T4 absorption impairment post-bariatric surgery underscore the potential utility of oral liquid formulations to mitigate malabsorption in some instances [83,84]. In conclusion, personalized and evidencebased approaches are essential in navigating the treatment of obesity-related thyroid disorders, ensuring optimal outcomes while minimizing risks and complications (Fig.…”

Subclinical Hypothyroidism in Patients with Obesity and Metabolic Syndrome: A Narrative Review

“…The possibility that the absorption of LT4 tablets can be impaired by bariatric surgery could support the usefulness of oral liquid formulations to improve malabsorption in some obese patients after bariatric surgery [ 64 , 65 ].…”