Abstract
Levothyroxine is commonly used to treat hypothyroidism. This study investigates
how far the intake of L-T4 influences body composition, energy expenditure,
respiratory quotient as well as strength, endurance and mobility in
premenopausal women who suffer from subclinical hypothyroidism. Twenty-five
women (27.36±5.77 years) with subclinical hypothyroidism were included
in the study. The intake of levothyroxine was assumed. Subjects were examined
immediately after study inclusion, after two months of levothyroxine use, and
after TSH was fully adjusted to the reference range. In all measurements TSH,
fT3 and fT4 were determined, body weight, body composition, energy expenditure
and the respiratory quotient were measured, and a test battery was performed to
identify strength, mobility and endurance capacity. TSH decreased from
5.95±0.99 μIU/ml at study inclusion to 1.2±0.33
μIU/ml after final trial. No change in weight, BMI, muscle mass,
fat mass, energy expenditure and respiratory quotient was observed
(p>0.05). A significant improvement in chest press (p=0.002),
leg extension (p<0.001), right-hand grip strength (p=0.009)
shoulder mobility (p<0.001), hip mobility (p=0.07), explosive
strength (p=0.041) and the anaerobic threshold (p=0.13) was
identified. Likewise, a non-significant (p=0.298) increase in left-hand
grip strength could be detected.In summary, although levothyroxine does not
positively affect body composition, energy expenditure and respiratory quotient,
it can improve strength, mobility and endurance performance. For this reason,
treatment with levothyroxine is recommended to improve exercise capacity in
subclinical hypothyroidism.
Key words
hypothyroidism - subclinical hypothyroidism - exercise - physical performance - body composition
