Remission of hypothyroidism in post-bariatric surgery patients

Hypothyroidism is commonly associated with obesity. While the effects of bariatric surgery on comorbidities such as type 2 diabetes and hypertension have been well studied, there is limited information regarding its benefits in obese patients diagnosed with and receiving treatment for hypothyroidism.This study aimed to evaluate the effects of bariatric surgery in patients with hypothyroidism, with particular focus on changes in levothyroxine (LT4) dosage and the prevalence of hypothyroidism remission post-surgery.

A retrospective study spanning seven years was conducted at the Obesity Clinic of KFMC (King Fahad Medical City-a public tertiary care center in Riyadh, Saudi Arabia), involving 163 patients with concurrent obesity and hypothyroidism who underwent bariatric surgery. Patient's medical charts and pharmacological treatment records were reviewed. Pre- and post-operative parameters, including weight, body mass index (BMI), thyroid status, thyroid-stimulating hormone, free thyroxine, LT4 dosage, and the type of bariatric surgery performed, were recorded. Continuous variables are presented as mean±SD (standard deviation) and as percentages. Student's t-test was used to analyze the difference between means, and data normality was assessed using the Shapiro-Wilk test.

Of the 163 patients, 14 (8.6%) were male and 149 (91.4%) were female, with an overall mean pre-operative BMI of 49.30 ± 9.49 kg/m². Prior to surgery, the mean LT4 dose was 118.25 ± 59.39 mcg, which significantly decreased to 83.13 ± 57.39 mcg post-surgery (P < 0.001), reflecting a 30% reduction. Additionally, 24 patients (14.7%) experienced remission from hypothyroidism, whereas 8 patients (4.9%) showed an increase in thyroxine dosage.

The study demonstrated a significant reduction in LT4 doses following bariatric surgery, suggesting that obesity may contribute to hypothyroidism. Bariatric surgery may improve thyroid function, potentially reducing the need for medication. Patients with hypothyroidism undergoing bariatric surgery should have their thyroid function closely monitored every 6-12 weeks post-operatively for 1-2 years, or until their nadir weight is reached, to allow for appropriate levothyroxine dose adjustments.