Thyroid Function in Children with Down Syndrome in the Polish Population: A Case-Control Study

Background: Patients with subclinical thyroid disease have few or no clinical symptoms of thyroid dysfunction and thus, laboratory diagnosis is needed. In this context, the objective of the current study was to analyze the prevalence rate and pattern of thyroid function in children with Down syndrome in the Polish population. Methods: A total of 30 children, aged 6-12 years, with cytogenetically confirmed Down syndrome were studied. The control group included 27 children. Results: Of the 30 patients with Down syndrome, 14 (46.7%) had abnormal thyroid profiles. Mean thyroid-stimulating hormone (TSH) and fT4 concentrations in children with Down syndrome were found to be significantly increased compared with the controls (4.30 +/- 1.9 mu IU/mL, 95% CI: 3.55-5.04 mu IU/mL vs. 3.10 +/- 1.47 mu IU/mL, 95% CI: 2.52-3.68 mu IU/mL, P = 0.013, 95% CI: 0.26-2.14, and 1.33 +/- 0.23 ng/dL, 95% CI: 1.25-1.42 vs. 1.19 +/- 0.14 ng/dL, 95% CI: 1.13-1.25, P = 0.008, 95% CI: 0.04-0.24, respectively). In Down syndrome, subclinical hypothyroidism was recognized in 10 children (33.3%) (high TSH and normal fT4 and fT3 levels). Two children (6.67%) had evident hypothyroidism (high TSH and low fT4). In the control group, subclinical hypothyroidism was diagnosed in four (14.8%) children. Conclusion: Children with Down syndrome may have increased secretion of TSH, even when thyroid hormone and autoantibodies are normal, suggesting that an isolated increase in TSH does not predispose the patient to the development of thyroid disease. We also recommend that all patients with Down syndrome should be screened for thyroid dysgenesis, since they have thyroid dysfunction more frequently as compared to the general healthy population.