Endocrine Abstracts

Background: Thyroid hormone plays a key role in bone mineral homeostasis and significant alterations in its circulating levels has been associated with impairment in skeletal growth during childhood. To date, bone effects of subclinical hypothyroidism (SH) has not been demonstrated yet, therefore the management of this condition is still debated.

Aim: To evaluate bone mineral density (BMD) in children with mild, persistent SH and the effects of two-years treatment with levothyroxine (L-T4) on their skeletal homeostasis.

Methods: Seventeen children (8 males), aged 8.7±1.03 years with mild (TSH levels between 4.2 and 10 mU/l), persistent (≥2 years from the diagnosis) and idiopathic SH were enrolled in the study, togheter with 17 age-, sex- and BMI- matched controls. At study entry, both groups underwent a complete clinical, laboratoristic and radiographic evaluation, by using the dual-energy X-ray densitometry (DXA) to evaluate their lumbar spine BMD. In the second phase of the study, SH children were treated for two years with L-T4 and then reassessed to evaluate possible changes in bone mineral status.

Results: At study entry, mean BMD Z-score was normal in SH subjects and comparable to controls (−0.41±0.42 vs −0.12±0.25, respectively, p ns). After two years of L-T4 therapy, a mild, but not significant, increase in BMD z-score was observed in SH children versus basal values (0.81±0.56, P=0.08).

Conclusions: Bone health, evaluated by lumbar spine DXA, is not impaired in SH children, despite long-term duration of idiopathic SH and two-years treatment with L-T4 did not change significantly their skeletal homeostasis.