Five-year prospective evaluation of thyroid function in girls with subclinical mild hypothyroidism of different etiology

Abstract

Aim: To follow-up for 5 years thyroid status evolution in 127 girls with mild (TSH 5-10 mU/l) subclinical hypothyroidism (SH) of different etiologies. Patients: The population was divided into two age-matched groups of 42 and 85 girls with either idiopathic (group A) or Hashimoto's thyroiditis (HT)-related SH (group B). Group B was in turn divided into three subgroups, according to whether SH was either isolated or associated with Turner syndrome (TS) or Down syndrome (DS). Results: At the end of follow-up the rate of girls who became euthyroid was higher in group A (61.9% vs 10.6%), whereas the rates of patients who remained SH (55.3% vs 26.2%), became overtly hypothyroid (30.6% vs 11.9%) or required levothyroxine (L-T 4 ) therapy (63.5% vs 23.8%) were higher in group B. Among the girls of group B, the risk of remaining SH or developing overt hypothyroidism was higher in the subgroups with TS or DS than in those with isolated HT. Conclusions: Long-term prognosis of mild and idiopathic SH is frequently benign, even though a L-T 4 treatment may be needed throughout follow-up in almost a quarter of cases; long-term prognosis is different in the girls with either idiopathic or HT-related SH; and the association with either TS or DS impairs the outcome of HT-related SH.

The Evolution of Thyroid Function after Presenting with Hashimoto Thyroiditis Is Different between Initially Euthyroid Girls with and Those without Turner Syndrome

“…In our prolonged prospective study, these results as a whole confirm the sporadic reports that an association with TS might be able to affect the course of HT in childhood by increasing the risk of thyroid functional deterioration over time [1,12,20,21] . Therefore, in light of these peculiarities, which seem to characterize the evolution of TS-related HT, strict monitoring of the thyroid status in girls with this condition probably has to be suggested (even in those patients who initially present with euthyroidism) in order to recognize at the proper time a possible shift from euthyroidism to hypothyroidism or hyperthyroidism.…”

“…The more severe long-term prognosis of thyroid function that was observed in TS-related HT was irrespective of potential confounding variables (age and serum TPOAb levels at HT diagnosis) and is not easily explained from a pathophysiological point of view. It has to be considered, however, that a more severe long-term prognosis of thyroid function was already reported even in HT children with Down syndrome [20][21][22] , i.e., another chromosomopathy which is known to be linked with an increased susceptibility to AITDs [23,24] .…”

Mild Hypothyroidism in Childhood: Who, When, and How Should Be Treated?

“…At the end of the study, 61.9% of girls with mild nonautoimmune SH normalized thyroid function, 26.2% maintained unchanged their TSH, and only 11.9% progressed to overt hypothyroidism. Conversely, in the group with autoimmune mild SH, a progressive deterioration of thyroid function was observed in 30.6% of girls, and only 10.6% normalized their TSH [60]. …”

“…Moreover, in girls with HT, the association with either Turner syndrome or DS further increased the risk of thyroid function deterioration [60]. …”

Analysis of the factors affecting the evolution over time of subclinical hypothyroidism in children

“…Pediatric studies on long-term evolution of SH in individuals with no apparent underlying thyroid disorders are few [10, 11, 17, 18]. …”