Relations of thyroid function to body weight: cross-sectional and longitudinal observations in a community-based sample.
BACKGROUND
Overt hypothyroidism and hyperthyroidism may be associated with weight gain and loss. We assessed whether variations in thyroid function within the reference (physiologic) range are associated with body weight.


METHODS
Framingham Offspring Study participants (n=2407) who attended 2 consecutive routine examinations, were not receiving thyroid hormone therapy, and had baseline serum thyrotropin (TSH) concentrations of 0.5 to 5.0 mIU/L and follow-up concentrations of 0.5 to 10.0 mIU/L were included in this study. Baseline TSH concentrations were related to body weight and body weight change during 3.5 years of follow-up.


RESULTS
At baseline, adjusted mean weight increased progressively from 64.5 to 70.2 kg in the lowest to highest TSH concentration quartiles in women (P< .001 for trend), and from 82.8 (lowest quartile) to 85.6 kg (highest quartile) in men (P= .007 for trend). During 3.5 years of follow-up, mean (SD) body weight increased by 1.5 (5.6) kg in women and 1.0 (5.0) kg in men. Baseline TSH concentrations were not associated with weight change during follow-up. However, an increase in TSH concentration at follow-up was positively associated with weight gain in women (0.5-2.3 kg across increasing quartiles of TSH concentration change; P< .001 for trend) and men (0.4-1.3 kg across quartiles of TSH concentration change; P= .007 for trend).


CONCLUSIONS
Thyroid function (as assessed by serum TSH concentration) within the reference range is associated with body weight in both sexes. Our findings raise the possibility that modest increases in serum TSH concentrations within the reference range may be associated with weight gain.
Fox
Caroline S
CS
National Heart, Lung, and Blood Institute's Framingham Heart Study, 73 Mt Wayte Ave, Ste 2, Framingham, MA 01702, USA. foxca@nhlbi.nih.gov
Pencina
Michael J
MJ
D'Agostino
Ralph B
RB
Murabito
Joanne M
JM
Seely
Ellen W
EW
Pearce
Elizabeth N
EN
Vasan
Ramachandran S
RS
D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood*; D015430:Weight Gain / Q000502:physiology*; D015431:Weight Loss / Q000502:physiology*
D013972:Thyrotropin