Low serum TSH levels are associated with low values of fat-free mass and body cell mass in the elderly

Till Ittermann,Marcus Dörr,Marcello R P Markus,Henry Völzke,Martin Bahls,Antje Steveling,Stephan B Felix,Matthias Nauck

doi:10.1038/s41598-021-90178-7

Abstract

Previous studies on the association between thyroid function and body composition are conflicting and showed strong differences across age groups. Our aim was to clarify age-specific associations of serum thyroid-stimulating hormone (TSH) levels with markers of body composition including body mass index (BMI), waist circumference, fat mass (FM), fat-free mass (FFM) and body cell mass (BCM). We used data from two independent population-based cohorts within the framework of the Study of Health in Pomerania. The study population included 5656 individuals aged 20 to 90 years. Markers of body composition were measured by bioelectrical impedance analysis. Serum TSH levels were significantly positively associated with BMI (β = 0.16; 95% confidence interval [CI]: 0.06 to 0.27), waist circumference (β = 0.35; 95% CI: 0.08 to 0.62) and FM (β = 0.32; 95% CI: 0.12 to 0.52), but not with FFM and BCM. Interaction analysis revealed positive associations of serum TSH levels with BMI, waist circumference, FM, FFM and BCM in individuals older than 60 years, while no such associations were observed in younger individuals. We demonstrated that lower serum TSH levels were accompanied with lower values of BMI, waist circumference, FM, FFM, and BCM in the elderly, while no such associations were observed in younger individuals.

Highlights

Previous studies on the association between thyroid function and body composition are conflicting and showed strong differences across age groups
fat-free mass (FFM) and body cell mass (BCM), were lower in the high thyroid-stimulating hormone (TSH) group compared to individuals with serum TSH levels within the reference range
In multivariable linear regression adjusted for age, sex, smoking status and study, serum TSH levels used as continuous variable were significantly positively associated with body mass index (BMI) (β = 0.16; 95% confidence interval [CI] = 0.06 to 0.27), waist circumference (β = 0.35; 95% CI = 0.08 to 0.62) and fat mass (FM) (β = 0.32; 95% CI = 0.12 to 0.52), but not with FFM and BCM (Table 2)

Summary

Introduction

Previous studies on the association between thyroid function and body composition are conflicting and showed strong differences across age groups. Our aim was to clarify age-specific associations of serum thyroid-stimulating hormone (TSH) levels with markers of body composition including body mass index (BMI), waist circumference, fat mass (FM), fat-free mass (FFM) and body cell mass (BCM). Interaction analysis revealed positive associations of serum TSH levels with BMI, waist circumference, FM, FFM and BCM in individuals older than 60 years, while no such associations were observed in younger individuals. With respect to thyroid dysfunction, several cross-sectional population-based studies in adults as well as in children demonstrated significant associations of high thyroid-stimulating hormone (TSH) with body mass index (BMI) and waist circumference[7,8,9,10,11,12]. In a cross-sectional, population-based study with 946 males aged 25 to 45 years no significant association between serum TSH levels and lean mass was o bserved[13]. Age; years Males Smoking status Former Current Body mass index; kg/m2 Waist circumference; cm Fat mass; kg Fat-free mass; kg Body cell mass; kg Systolic blood pressure; mmHg Diastolic blood pressure; mmHg SPINA-GT SPINA-GD Jostel’s TSH index

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