Subclinical hypothyroidism (SH or hyperthyrotropinemia) is a biochemical condition defined as elevated serum TSH concentrations and normal thyroxine (FT4). Generally, it is asymptomatic and is distinguished in mild (TSH between the upper limit and 9.9 μUI/ml) and severe (TSH equal to or higher than 10 μUI/ml). Replacement L-thyroxine treatment is requested for the severe form, while mild form treatment is still debated. In children, SH is usually a benign and remitting condition and progression to overt hypothyroidism is uncommon. By contrast, the risk of a deterioration of thyroid status is higher in children with
SH and Hashimoto’s thyroiditis or chromosomal abnormalities, such as Turner syndrome or trisomy 21. Thyroid function is involved in many aspects of growth and development; therefore, it is important to evaluate whether untreated hyperthyrotropinemia implies longterm consequences. On the contrary, mild thyroid dysfunction is improperly considered the cause of some clinical issues, such as obesity, sleep disorders and constipation. Finally, testing only TSH and FT4 in the suspicion of hypothyroidism is highly recommended.
