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- Title
The effects of thyroid hormones on brown adipose tissue in humans: a PET-CT study.
- Authors
Zhang, Qiongyue; Miao, Qing; Ye, Hongying; Zhang, Zhaoyun; Zuo, Chuantao; Hua, Fengchun; Guan, Yihui; Li, Yiming
- Abstract
Background: Brown adipose tissue (BAT) is important for energy expenditure through thermogenesis, although its regulatory factors are not well known in humans. There is evidence suggesting that thyroid hormones affect BAT functions in some mammals, but the effects of thyroid hormones on BAT activity in humans are still unclear. The aim of this study was to investigate the effects of thyroid hormones on glucose metabolism of BAT and other organs in humans. Methods Nine Graves' disease-caused hyperthyroid patients who were newly diagnosed and untreated were studied. Putative brown adipose tissue activity was determined by the integrated 18F-fluorodeoxyglucose (18F-FDG) positronemission tomography and computed tomography (PET-CT). All hyperthyroid patientswere treatedwithmethimazole and had been monitored until their symptoms disappeared and thyroid hormone levels returned to normal. At the end, a second PET-CT scan was performed. The average follow-up period was 77 days. Meanwhile, compared with a group of seventy-five brown adipose tissue-negative controls, thyroid hormones of seventy-five BAT-positive healthy subjects were measured. Results Active brown adipose tissuewas not present in any of the hyperthyroid patients. However, one patient with normalized thyroid function showed active BAT after therapy. The free T3 levels and free T4 levels were significantly lower in the 75 BATpositive subjects than in the BAT-negative subjects. All hyperthyroid patients showed symmetrically increased uptake of fluorodeoxyglucose in skeletalmuscles before treatment, whereas, the standardized uptake value was substantially decreased after treatment. Conclusions Abnormally high circulating thyroid hormone levelsmay not increase brown adipose tissue activity, which may be limited by the increased obligatory thermogenesis of muscle in adult humans.
- Publication
Diabetes/Metabolism Research & Reviews, 2014, Vol 30, Issue 6, p513
- ISSN
1520-7552
- Publication type
Article
- DOI
10.1002/dmrr.2556