Background: Thyroid dysfunction may predispose to imbalanced body composition.
Objective and hypotheses: The aim of the study is to evaluate bone, muscle and fat mass in teenagers with congenital hypothyroidism and correlate their bone profile with laboratory parameters, in an effort to offer more effective lifestyle counselling.
Method: Adolescents diagnosed with congenital hypothyroidism through neonatal screening underwent thorough clinical examination, thyroid function tests (TFTs) and basic bone profile, as well as bone mineral density scan, using dual-energy X-ray absorptiometry (DXA). For statistical purposes, a group of 57 healthy age- and sex-matched controls was also studied.
Results: To date, 18 teenagers have been assessed, aged 1418 years (12 female subjects); 4 with thyroid gland agenesis, 10 with ectopic thyroid gland, 2 with hypoplastic thyroid gland and 2 with dysormonogenesis. Five patients report a total of five post-traumatic fractures of long bones. 55% receive adequate calcium through their diet and only 33% exercise regularly. Their laboratory results (lipid profile, TFTs, 25(OH)D, parathormone) were within reference range, with a tendency of high-normal TSH values amongst boys. Compared to controls, the patients were heavier, with marginally higher fat mass, whereas their bone and muscle mass were comparable. A positive correlation was found between body weight and fat mass, which in turn was negatively correlated to vitamin D levels (r=−0.77, P<0.01).
Conclusion: Overweight patients with congenital hypothyroidism tend to have more pronounced adipose tissue accumulation and lower vitamin D levels, therefore they should be targeted towards regular exercise and a balanced diet, with adequate calcium intake. In patients whose hypothyroidism is under control, bone and muscle mass are not particularly affected.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology