title: TREATMENT OF SUBCLINICAL HYPERTHYROIDISM: EFFECT ON BODY COMPOSITION.
abstract: BACKGROUND
  subclinical hyperthyroidism (SHT) is associated with harmful effects on cardiovascular system, bone metabolism and progression to clinical hyperthyroidism. Loss of weight is a common fact in patients with clinical hyperthyroidism and of particular relevance in elderly patients.
  
  
  OBJECTIVE
  to assess changes in body composition after radioiodine therapy for SHT due to toxic nodular goiter.
  
  
  METHODS
  prospective controlled cohort study. Patients with persistent SHT due to toxic nodular goiter were purposed to receive treatment with radioiodine (treatment group) or to delay treatment until the study was over (control group). All treated patients received 555 MBq of ¹³¹I. Body composition (lean mass, fat mass and bone mineral content) was determined by dual-energy X-ray absorptiometry (DEXA) at baseline and 12 months after.
  
  
  RESULTS
  twenty-nine patients were studied (age 69.5 ± 11.5; 75.9% women; BMI 27.1 ± 5.7 kg/m²; serum thyrotropin (TSH) 0.20 ± 0.21 μUI/mL; serum free thyroxine (T4) 1.01 ± 0.19 ng/dL), 17 belonging to the treatment group and 12 to the control group. Study groups were comparable, although there was a trend for the treatment group to have more fat mass. No longitudinal changes in body composition were noted in either group, except for a trend to gain fat mass. However, when individuals with age > 65 years were selected, only patients who received radioiodine therapy showed a significant increase in body weight (from 64.1 ± 10.0 to 66.9 ± 9.2 kg), BMI (from 27.3 ± 4.8 to 28.7 ± 4.5 kg/m²), fat mass (from 26.1 ± 8.5 to 27.8 ± 7.9 kg), lean mass (from 36.3 ± 0.4 to 37.4 ± 0.4 kg) and skeletal muscle mass index (SMI) (from 6.0 ± 0.6 to 6.3 ± 0.6 kg/m²).
  
  
  CONCLUSIONS
  treatment of SHT has impact on body composition in subjects older than 65 years. Weight gain reflects increases in fat and, more interestingly, in lean mass.
authors.affiliation: Hospital Universitario Miguel Servet, Department of Endocrinology & Nutrition.. dbojcarc@gmail.com.
authors.forename: Diana
authors.initials: D
authors.lastname: Boj-Carceller
authors.affiliation: Hospital Universitario Miguel Servet, Department of Endocrinology & Nutrition.. dbojcarc@gmail.com.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sanz-París
authors.affiliation: Department of Biostadistics and Public Health, University of Zaragoza.. dbojcarc@gmail.com.
authors.forename: Enrique
authors.initials: E
authors.lastname: Sánchez-Oriz
authors.affiliation: Department of Biostadistics and Public Health, University of Zaragoza.. dbojcarc@gmail.com.
authors.forename: Rafael
authors.initials: R
authors.lastname: García-Foncillas López
authors.affiliation: Hospital Universitario Miguel Servet, Service of Clinical Biochemistry.. dbojcarc@gmail.com.
authors.forename: Pilar
authors.initials: P
authors.lastname: Calmarza-Calmarza
authors.affiliation: Hospital General de la Defensa Orad y Gajías, Department of Endocrinology.. dbojcarc@gmail.com.
authors.forename: Vicente
authors.initials: V
authors.lastname: Blay-Cortes
authors.affiliation: Hospital Universitario Miguel Servet, Department of Nuclear Medicine. Spain.. dbojcarc@gmail.com.
authors.forename: Ma Dolores
authors.initials: MD
authors.lastname: Abós-Olivares
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D015331:Cohort Studies; D005260:Female; D006044:Goiter, Nodular / Q000378:metabolism / Q000532:radiotherapy; D006801:Humans; D006980:Hyperthyroidism / Q000378:metabolism* / Q000532:radiotherapy*; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013963:Thyroid Hormones / Q000097:blood; D015430:Weight Gain
chemical_list: D007457:Iodine Radioisotopes; D013963:Thyroid Hormones