Thyroid function and body weight: a community-based longitudinal study.

Lena Bjergved,Lars Ovesen,Nils Knudsen,Anne Krejbjerg,Peter Laurberg,Lone Banke Rasmussen,Hans Perrild,Torben Jørgensen,Nicholas John Timpson

doi:10.1371/journal.pone.0093515

Abstract

ObjectiveBody weight and overt thyroid dysfunction are associated. Cross-sectional population-based studies have repeatedly found that thyroid hormone levels, even within the normal reference range, might be associated with body weight. However, for longitudinal data, the association is less clear. Thus, we tested the association between serum thyrotropin (TSH) and body weight in a community-based sample of adult persons followed for 11 years.MethodsA random sample of 4,649 persons aged 18–65 years from a general population participated in the DanThyr study in 1997–8. We included 2,102 individuals who participated at 11-year follow-up, without current or former treatment for thyroid disease and with measurements of TSH and weight at both examinations. Multiple linear regression models were used, stratified by sex and adjusted for age, smoking status, and leisure time physical activity.ResultsBaseline TSH concentration was not associated with change in weight (women, P = 0.17; men, P = 0.72), and baseline body mass index (BMI) was not associated with change in TSH (women, P = 0.21; men, P = 0.85). Change in serum TSH and change in weight were significantly associated in both sexes. Weight increased by 0.3 kg (95% confidence interval [CI] 0.1, 0.4, P = 0.005) in women and 0.8 kg (95% CI 0.1, 1.4, P = 0.02) in men for every one unit TSH (mU/L) increase.ConclusionsTSH levels were not a determinant of future weight changes, and BMI was not a determinant for TSH changes, but an association between weight change and TSH change was present.

Highlights

The thyroid gland produces thyroid hormones, which regulate gene transcription and metabolism throughout the body
Baseline TSH concentration was not associated with change in weight, and baseline body mass index (BMI) was not associated with change in TSH
Change in serum TSH and change in weight were significantly associated in both sexes

Summary

Introduction

The thyroid gland produces thyroid hormones, which regulate gene transcription and metabolism throughout the body. Thyroid hormones play a key role in the basal metabolic rate, thermogenesis, as well as in the regulation of body metabolism in starved and fed states [1,2,3]. Overt thyroid disease is associated with marked changes in energy expenditure and body weight, with enhanced protein breakdown, lipolysis [4,5], and typically weight loss in hyperthyroidism, and the reverse in hypothyroidism [6]. Adipose tissue has been recognized as a major endocrine organ, involved in the regulation of thermogenesis, food intake, and energy expenditure, e.g., the change between fed and starved state [3]. A decrease in TSH was observed following diet-, exercise-, and behavior therapyinduced weight loss in children and adolescents [10,11]. The exact mechanisms are as yet unexplained and the temporality is debated

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