TSH and free triiodothyronine concentrations are associated
with weight loss in a lifestyle intervention and weight regain
afterwards in obese children
Barbara Wolters, Nina Lass and Thomas Reinehr
Department of Pediatric Endocrinology, Diabetes and Nutrition Medicine, Vestische Hospital for Children and Children Datteln, University of
Witten/Herdecke, Dr F Steiner Street 5, D-45711 Datteln, Germany
(Correspondence should be addressed to T Reinehr; Email: email@example.com)
Objective: The impact ofthyroid hormones on weight loss in lifestyle interventions and on weight regain
afterwards is unknown. Therefore, we studied the relationships between TSH, free triiodothyronine
(fT3), free thyroxine (fT4), and weight status, as well as their changes during and after a lifestyle
intervention in obese children.
Materials and methods: We evaluated the weight status as BMI–SDS in 477 obese children (mean age
10.6G2.7 years, 46% male, mean BMI 28.1G4.5 kg/m2) participating in a 1-year lifestyle
intervention in a 2-year longitudinal study. Changes in BMI–SDS at 1 and 2 years were correlated
with TSH, fT3, and fT4concentrations at baseline and their changes during the intervention.
Results: A decrease in BMI–SDS during the intervention period (K0.32G0.38; P!0.001) was
significantly positively associated with baseline TSH and fT3in multiple linear regression analyses
adjusted for age, sex, pubertal stage, and baseline BMI–SDS. An increase in BMI–SDS after the end of
the intervention (C0.05G0.36; PZ0.011) was significantly related to the decreases in TSH and fT3
during the intervention in multiple linear regression analyses adjusted for change in BMI–SDS during
the intervention. In contrast to children with weight maintenance, children with weight regain after
the end of the intervention demonstrated a decrease in their TSH levels (K0.1G1.6 vs C0.2G
1.6 mU/l; PZ0.03) and fT3(K0.2G1.1 vs C0.3G1.6 pg/ml; P!0.001) during the intervention.
Conclusions: The decreases in TSH and fT3concentrations during the lifestyle intervention were
associated with weight regain after the intervention. Future studies should confirm that the decreases
in TSH and fT3levels associated with weight loss are related to the change in metabolism such as
resting energy expenditure.
European Journal of Endocrinology 168 323–329
A moderate elevation of TSH concentrations, which is
associated with triiodothyronine (T3) values in or
slightly above the upper normal range, is frequently
found in obese humans (1, 2, 3, 4, 5, 6, 7, 8, 9). These
changes are reversible in weight loss independent of
whether weight loss is obtained through diet or bariatric
surgery (2, 7, 8, 10, 11, 12). Furthermore, a positive
correlation between weight gain during 5 years and a
progressive increase in serum TSH has also been
reported (13). These findings suggest that the increase
in TSH and T3concentrations in obese subjects seems to
The underlying mechanisms of the increases in TSH
and free T3(fT3) levels in obesity are largely unknown
(1, 14). For example, a derangement in the hypo-
thalamic–pituitary axis, an impaired feedback due to a
lowered number of T3receptors in the hypothalamus
(thyroid hormone resistance), and a decrease in
peripheral deiodinase activity have been postulated
(2). Furthermore, non-synonymous mutations in the
TSHR gene have been reported as a cause of increased
TSH levels in obesity, but these mutations are rare (15).
Additionally, seronegative autoimmune thyroiditis has
been suggested since thyroid hypoechogenicity at
ultrasound has been reported and antithyroid
antibodies are frequently negative in obese children
with elevated TSH and fT3levels (2, 15, 16). However,
cytological samples obtained in obese children with
elevated TSH levels, hypoechogenicity in ultrasound,
and negative for thyroid autoantibodies have been
reported to be normal, and, thus, excluded an
autoimmune disorder (16). A possible explanation for
thyroid hypoechogenicity at ultrasound observed in
obese children could be the existence of a low-grade
inflammation, a known characteristic of obesity (2).
However, the most favored hypothesis of increased TSH
European Journal of Endocrinology (2013) 168 323–329ISSN 0804-4643
q 2013 European Society of EndocrinologyDOI: 10.1530/EJE-12-0981
Online version via www.eje-online.org
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Received 23 September 2012
Accepted 3 December 2012
Thyroid hormones and changes in weight status
EUROPEAN JOURNAL OF ENDOCRINOLOGY (2013) 168