Association Between Serum TSH Concentration Within the Normal Range and Adiposity

Background: Overt hypothyroidism is clearly related to body weight gain and greater adiposity, but the range of hormonal change in serum TSH concentration associated with weight gain remains a focus of debate.

Aim: The aim of this review was to assess studies that evaluated the relationship between anthropometric measures and serum TSH concentration in euthyroid subjects.

Methods: Studies held on the Ovid MEDLINE database were searched and original articles published from 2000 to 2010 were included. The literature search was restricted to studies conducted in humans aged 18 years or older and written in English, Spanish, or Portuguese. Studies that evaluated the association between anthropometric measures and serum TSH within the normal range as the primary objective, as well as additional analysis, were included.

Results: A total of 29 studies met the inclusion criteria. Of the 29 studies, 18 showed a positive relationship between measures of adiposity and serum TSH. Despite the plausibility of this association, only two studies reported longitudinal findings. The influence of smoking on the association between serum TSH and anthropometric measures was evaluated in only three studies and remains unclear.

Conclusion: Thus, further longitudinal studies are needed to better understand the mechanisms by which TSH concentration might impact body weight.