Improvement of Hypothyroidism after Laparoscopic Roux-en-Y Gastric Bypass for Morbid Obesity

Background: Laparoscopic Roux-en-Y gastric bypass (LRYGBP) has been very effective in managing a broad range of morbid obesity-related co-morbidities. We report a beneficial effect of LRYGBP that has not been previously observed. Methods: Between December 1999 and September 2002, 224 patients underwent LRYGBP. Preoperative assessment for hypothyroidism and follow-up data were prospectively collected in our database. Improved thyroid function (ITF) or unchanged thyroid function (UTF) was determined by comparison of preoperative and postoperative thyroxine requirements. Results: 23 of 224 patients (10.3%) were treated preoperatively for hypothyroidism. During a median follow-up of 17 months, hypothyroidism was improved in 10/23 patients (43.5%). 2 patients had complete resolution, and the remaining 8 had reduction (14%-50%) of their thyroxine requirements. ITF occurred at a mean follow-up of 8.9 months and at a mean excess weight loss (EWL) of 57%. 6 of the 8 patients (75%) with ITF ≥ 25% had EWL >90% at last follow-up, compared to 1 out of 15 patients (6.6%) with UTF or <25% improvement (P =0.001). Comparison of patients with ITF and UTF over time during a 20-month follow-up, showed no significant difference in mean body mass index (BMI) and mean percentage of EWL. Conclusion: Improvement of hypothyroidism may be an additional benefit of bariatric surgery that has not been previously reported. Reduction of thyroxine requirements is most likely the result of the decrease in the BMI.