Thyroid function is not associated with brown adipose tissue volume and 18F-fluorodeoxyglucose uptake in young euthyroid adults

European Journal of Endocrinology, vol. 185, pp. 209–218

Abstract

PURPOSE: Thyroid hormones (THs) are important mediators of brown adipose tissue (BAT) differentiation. However, the association of TH concentrations with human BAT is unclear. The present work examines the associations between circulating thyroid-stimulating hormone (TSH) and THs concentrations (i.e. free triiodothyronine, FT3, and free thyroxine, FT4), under thermoneutral (22-23°C) and cold-induced conditions, and BAT volume, 18F-fluorodeoxyglucose (18F-FDG) uptake and mean radiodensity. METHODS: A total of 106 young healthy, euthyroid adults (34 men/72 women; 22.0 ± 2.1 years old; 24.9 ± 4.6 kg/m2) participated in this cross-sectional study. BAT volume, 18F-FDG uptake and mean radiodensity were assessed after 2 h of personalized (i.e. contemplating each individual's shivering threshold) cold exposure via positron emission tomography/computed tomography (PET/CT) static scanning. TSH and THs levels were determined before (thermoneutral) and 1 h after the cold exposure. RESULTS: Cold exposure increased circulating FT4 (P = 0.038) and reduced TSH levels (P ≤ 0.001). Conversely, the FT3 serum concentration was not modified by cold exposure (P = 0.435). No associations were found between the TSH and THs thermoneutral (all P > 0.111) or cold-induced levels (all P > 0.067) and BAT volume, 18F-FDG uptake and mean radiodensity. These findings were independent of sex and BMI. CONCLUSIONS: Thyroid function is modulated by cold exposure, yet it is not associated with BAT volume or glucose metabolism assessed after 2 h of cold exposure in young healthy, euthyroid adults.

Authors 8

1. Elisa Merchán-Ramírez corresponding

   Universidad de Granada

   Affiliation as printed

   1PROFITH “PROmoting FITness and Health through Physical Activity” Research Group, Department of Physical and Sports Education, Sport and Health University Research Institute (iMUDS), Faculty of Sports Science, University of Granada, Granada, Spain

2. Guillermo Sánchez‐Delgado

   Pennington Biomedical Research Center · Universidad de Granada

   Affiliation as printed

   1PROFITH “PROmoting FITness and Health through Physical Activity” Research Group, Department of Physical and Sports Education, Sport and Health University Research Institute (iMUDS), Faculty of Sports Science, University of Granada, Granada, Spain

   2Pennington Biomedical Research Center, Baton Rouge, Louisiano, USA

3. Cristina Arrizabalaga-Arriazu

   Fundación Hospital de Jove

   Affiliation as printed

   3Department of Endocrinology, Fundación Hospital de Jove, Gijón, Spain

4. Borja Martínez‐Téllez Aachen 4Department of Medicine Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular Medicine

   Leiden University · Universidad de Granada · Leiden University Medical Center

   Affiliation as printed

   1PROFITH “PROmoting FITness and Health through Physical Activity” Research Group, Department of Physical and Sports Education, Sport and Health University Research Institute (iMUDS), Faculty of Sports Science, University of Granada, Granada, Spain

   4Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands

5. Andrea Méndez-Gutiérrez

   Universidad de Granada · Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition · Instituto de Investigación Biosanitaria de Granada · Centro de Investigación Biomédica en Red

   Affiliation as printed

   5Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology “José Mataix” Center of Biomedical Research, University of Granada, Granada, Spain

   6Instituto de Investigación Biosanitaria (Ibs. Granada), Granada, Spain

   7CIBER Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Madrid, Spain

6. Manuel Muñoz‐Torres

   Universidad de Granada · Instituto de Salud Carlos III · Instituto de Investigación Biosanitaria de Granada · Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable

   Affiliation as printed

   10Endocrinology and Nutrition Service, University Hospital San Cecilio, Granada, Spain

   6Instituto de Investigación Biosanitaria (Ibs. Granada), Granada, Spain

   8Department of Medicine, University of Granada, Granada, Spain

   9CIBERFES, Instituto de Salud Carlos III, Granada, Spain

7. J.M. Llamas Elvira

   Instituto de Investigación Biosanitaria de Granada · Hospital Universitario Virgen de las Nieves

   Affiliation as printed

   11Nuclear Medicine Service, Virgen de las Nieves University Hospital, Granada, Spain

   6Instituto de Investigación Biosanitaria (Ibs. Granada), Granada, Spain

8. Jonatan R. Ruiz

   Universidad de Granada

   Affiliation as printed

   1PROFITH “PROmoting FITness and Health through Physical Activity” Research Group, Department of Physical and Sports Education, Sport and Health University Research Institute (iMUDS), Faculty of Sports Science, University of Granada, Granada, Spain