title: Effect of subclinical hypothyroidism on body fluid compartments.
abstract: OBJECTIVE
  The present study was aimed to assess the effects of subclinical hypothyroidism on body composition (BC).
  
  
  METHODS
  Thirty-one women (age: 37 +/- 9.9 years) with a wide range of body mass index (BMI) were studied. Subclinical hypothyroidism was defined by a basal TSH > or = 4 mU/L and/or TRH stimulated peak > or = 30 mU/L.
  
  
  METHODS
  For each subject, weight, height, BMI, multifrequency bioelectrical impedance spectroscopy (BIS) and D2O and NaBr dilution tests were performed to assessed total body water (TBW) and extracellular water (ECW). Thyroid function (basal and TRH stimulated TSH, free T3, and free T4) were determined from fasting blood samples for all subjects. Total body dual energy X-ray absorptiometry (DXA) were used to measure fat mass (FM) and lean mass (Lean).
  
  
  RESULTS
  The results of BIS were compared with the TBW and ECW estimated by the dilution techniques on the same individuals. The correlation was R2 = 0.65 for impedance at 5 kHz and ECW by NaBr and R2 = 0.72 for impedance at 100 kHz and TBW by D2O. Intracellular water (ICW) was calculated as differences between TBW and ECW measured by dilution methods. Percent of ECW and ICW were related to BMI (ANOVA, p < 0.001). No difference in TBW, body water distribution and body composition related to thyroid function was demonstrated.
  
  
  CONCLUSIONS
  In our patients affected with subclinical hypothyroidism, with or without obesity, only obesity appeared related to TBW, ECW and ICW; the subclinical hypothyroidism, on the contrary, had no effect on compartments of body fluids. Bioimpedance is a valid tool to assess body fluid distribution in subclinical hypothyroidism.
authors.affiliation: Human Nutrition Unit, University of Rome Tor Vergata, Italy. DELORENZO@UNIROMA2.IT
authors.forename: A
authors.initials: A
authors.lastname: De Lorenzo
authors.forename: A
authors.initials: A
authors.lastname: Andreoli
authors.forename: A
authors.initials: A
authors.lastname: Fusco
authors.forename: A
authors.initials: A
authors.lastname: Magnani
authors.forename: N
authors.initials: N
authors.lastname: D'Orazio
authors.forename: A
authors.initials: A
authors.lastname: Bertoli
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001825:Body Fluid Compartments / Q000502:physiology*; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D016022:Case-Control Studies; D004487:Edema / Q000503:physiopathology; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000503:physiopathology*; D009765:Obesity / Q000503:physiopathology; D011897:Random Allocation; D013223:Statistics as Topic; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood
chemical_list: D013972:Thyrotropin