Thyroid Stimulating Hormone Level at Diagnosis as a Predictor of Persistent Subclinical Hypothyroidism in Children with Down Syndrome

Objective

To evaluate subclinical hypothyroidism in a cohort of children with Down syndrome and identify a TSH level at the time of diagnosis to predict persistent hypothyroidism.

Methods

192 children (age <3 years) with Down syndrome, registered in the Genetic Clinic of a referral tertiary care Hospital from 2010 to 2015 were evaluated with thyroid function test at initial visits and subsequently based on standard protocol. Children with subclinical hypothyroidism were evaluated at 3 years of age after discontinuation of thyroxine for 3 months.

Results

47 (24.5%) children had elevated TSH and among them 43 (91.5%) had subclinical hypothyroidism. Among the subclinical hypothyroidism group, 25 (73.5%) had transient hypothyroidism and 9 (26.5%) persistent hypothyroidism. Initial TSH level at the time of diagnosis was higher in persistent hypothyroidism group as compared to transient group (P= 0.003). The best cut-off level for prediction of persistent hypothyroidism for initial TSH level was 11.6 mIU/L.

Conclusion

Subclinical hypothyroidism, especially transient, is the commonest form of thyroid dysfunction in children with Down syndrome. The initial TSH level may help to predict the possibility of persistence of hypothyroidism.