title: Prevalence of subclinical hypothyroidism in a morbidly obese population and improvement after weight loss induced by Roux-en-Y gastric bypass.
abstract: BACKGROUND
  There are many studies concerning thyroid function in obesity, and some of them describe higher TSH levels in obese subjects. Few studies evaluated long-term changes in thyroid function caused by weight loss after bariatric surgery. Our aims were to evaluate the prevalence of subclinical hypothyroidism (SH) in a morbidly obese population and to analyze the effect of weight loss induced by Roux-en-Y gastric bypass (RYGBP) on TSH and thyroid hormone (TH) levels.
  
  
  METHODS
  TSH, free thyroxine (fT4) and total triiodothyronine (T3) levels were analyzed before and 12 months after RYGBP in patients with grade III or grade II obesity with co-morbidities. Subjects taking TH and/or with positive antithyroid antibodies and/or with overt hypothyroidism were excluded.
  
  
  RESULTS
  72 subjects (62F/10M), with mean age 39.6+/-9.8 years and mean BMI 53.0+/-10.4 kg/m2 were studied. The prevalence of SH before RYGBP was 25% (n=18). There was a significant post-surgical decrease in BMI in the whole population, as well as in SH patients. In the SH group and normal TSH group, there was a decrease in TSH and T3, but not in fT4. TSH was not correlated with initial BMI or percent change in BMI. TSH concentrations reached normal values in all SH patients after RYGBP.
  
  
  CONCLUSIONS
  Our data confirm that severe obesity is associated with increased TSH. The decrease in TSH was independent of BMI, but occurred in all SH patients. A putative effect of weight reduction on the improvement of SH in all patients may be an additional benefit of bariatric surgery.
authors.affiliation: Obesity and Metabolic Syndrome Unit, Endocrinology Service, Hospital das Clínicas, University of São Paulo Medical School, São Paulo, Brazil. crismoulin@yahoo.com.br
authors.forename: Cristiane M
authors.initials: CM
authors.lastname: Moulin de Moraes
authors.forename: Marcio C
authors.initials: MC
authors.lastname: Mancini
authors.forename: Maria Edna
authors.initials: ME
authors.lastname: de Melo
authors.forename: Daniela Andraus
authors.initials: DA
authors.lastname: Figueiredo
authors.forename: Sandra Mara F
authors.initials: SM
authors.lastname: Villares
authors.forename: Alessandra
authors.initials: A
authors.lastname: Rascovski
authors.forename: Bruno
authors.initials: B
authors.lastname: Zilberstein
authors.forename: Alfredo
authors.initials: A
authors.lastname: Halpern
mesh_terms: D000328:Adult; D000713:Anastomosis, Roux-en-Y; D005260:Female; D015390:Gastric Bypass / Q000379:methods; D006801:Humans; D007037:Hypothyroidism / Q000150:complications* / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood / Q000150:complications* / Q000601:surgery; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D015431:Weight Loss
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine