Thyroid evaluation of children and adolescents with Williams syndrome in Zhejiang Province.

BACKGROUND: The objective of the study was to describe the prevalence of abnormal thyroid function and volume in children and adolescents with Williams syndrome (WS) in Zhejiang Province, China.

METHODS: Thyroid function, including thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), and thyroid antibodies (thyroid peroxidase and thyroglobulin) were measured in 83 patients with WS, aged 0.2-16.5 years. Twenty-three patients were followed for an average of 1.7 years (0.4-4.1), and multiple TSH determinations were considered. Thyroid ultrasonography was performed on 49 patients.

RESULTS: One patient was diagnosed with overt hypothyroidism, and 23 patients (27%) had subclinical hypothyroidism (SH). Thyroid antibodies were absent in all patients. In five age groups (0-1 years, 1-3 years, 3-6 years, 6-9 years, 9-18 years), the prevalence of patients with subclinical hypothyroidism was 25%, 28.5%, 44.4%, 16.7% and 4.7%, respectively. Through ultrasound examination, 21 patients (42%) were observed to have thyroid hypoplasia (TH), and there were no cases of thyroid haemiagenesis. The incidence rate of TH increased with age, rising from 20% in the youngest group to 66% in the oldest.

CONCLUSIONS: SH and TH is common in children and adolescents with WS. Yearly evaluation of thyroid must be performed in all patients in this population, regardless of the result of the neonatal screening. Age under 6 years and existing thyroid abnormalities are risk factors for developing SH, and a shorter follow-up interval is needed for screening in these individuals, SH is often self-limiting, and clinicians should be alert to overt hypothyroidism.