Subclinical hypothyroidism and its relation to obesity in patients before and after Roux-en-Y gastric bypass

Abstract Background Subclinical hypothyroidism (SH), defined as a raised serum thyroid-stimulating hormone (TSH) with a normal free thyroxine (FT4), is occasionally observed in morbidly obese patients. Objectives It is currently not known whether thyroid hormone treatment is indicated. The aim of the present study was to assess the changes in thyroid hormone levels in thyroxine-naive patients with SH in response to weight loss induced by Roux-en-Y gastric bypass (RYGB). Setting General hospital specialized in bariatric surgery. Methods Serum levels of TSH and FT4 were measured at baseline in 503 patients presenting for RYGB. In patients diagnosed with SH, these measurements were repeated 12 months postoperatively. Results SH de novo was present in 71 out of 503 patients (14.1%). One-year follow-up was available in 61 out of 71 patients (86%). TSH level>10 mU/L was observed in 3 patients (.5%). RYGB induced a decrease in BMI from 47±8 kg/m 2 to 33±6 kg/m 2 at 12-month follow-up ( P P P Conclusion The prevalence of SH de novo is high in morbidly obese patients. After RYGB it resolves in about 90% of patients. This high degree of spontaneous recovery suggests that follow-up alone is sufficient in the majority of patients.