BACKGROUND
Bariatric surgery (weight-loss surgery) is a successful treatment for obesity. Bariatric surgery is an operation to change the digestive system to limit food intake and decrease hunger. This can be done by removing part of the stomach to make it smaller (sleeve gastrectomy) or by bypassing the stomach completely (gastric bypass). Bariatric surgery is generally safe, but problems after the procedure can occur. The most common complications seen after this type of surgery are bleeding, infections, hernias and blood clots.

It is not clear if patients with hypothyroidism have higher chances of complications after bariatric surgery. Studies on hypothyroid patients undergoing any surgery showed that they have a higher chance of infection and heart problems after surgery, especially if the thyroid levels were not in the normal range before the surgery. But those studies did not specifically look at patients who got bariatric surgery. This study was done to find out the risks of bariatric surgery in patients with hypothyroidism.

THE FULL ARTICLE TITLE
Meneghini V et al. Adverse outcomes in patients with hypothyroidism undergoing bariatric surgery: a retrospective study using TriNetX. J Clin Endocrinol Metab 2025;16:dgaf519; doi: 10.1210/clinem/dgaf519. PMID: 40971953.

SUMMARY OF THE STUDY
This authors of this study looked at medical records of adults with obesity who underwent sleeve gastrectomy or gastric bypass between 2005 and 2024 in 141 health care organizations. They divided the surgical patients in two groups: Group 1: patients with hypothyroidism diagnosed before the surgery, and all were prescribed thyroid hormone replacement; Group 2 (control): patients who were NOT hypothyroid before or after surgery and were not taking thyroid hormone replacement.

There were 5,700 patients in each group. Most of the patients were women and the average age was 46 years old. They also looked at a third group of patients with hypothyroidism and obesity who did NOT get bariatric surgery.

Right after bariatric surgery, hypothyroid patients had a higher chance of being readmitted (25% higher), having a hernia (56% higher), and biliary disease (39% higher). In addition, this group of patients had more medical problems later, for example strokes (25% higher), diabetes (39% higher), high lipids, osteoporosis and nutritional deficiencies. These complications were seen even if thyroid levels were normal before the surgery. The chances of complications were generally higher in patients who got gastric bypass as compared to sleeve gastrectomy. On the other hand, when compared to the third group of patients who did NOT get surgery, those who had bariatric surgery had lower chances of death, diabetes, high blood pressure, high lipids and cardiovascular problems.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study shows that adults with obesity and hypothyroidism who get bariatric surgery have higher chances of problems after the surgery. Many of these complications happened more often in people who had gastric bypass than in people who had sleeve gastrectomy. The good news is that people who had bariatric surgery were less likely to die or have heart problems than similar people who did not have the surgery. Even though complications happened in patients with normal thyroid levels, it is still good practice to check that patients’ thyroid levels are normal before any surgery.

— Susana Ebner MD

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