The prevalence and spectrum of thyroid dysfunction among children with Down syndrome attending the paediatric services at two tertiary hospitals in Pretoria, South Africa

Abstract

BACKGROUND : Down syndrome (DS) is the most common chromosomal abnormality in the paediatric setting, and thyroid dysfunction is more commonly encountered in this population than among the general population. The literature shows that the most common type of thyroid dysfunction seen in these children is subclinical hypothyroidism. OBJECTIVE : The purpose of this study was to establish the prevalence and spectrum of thyroid disease in this population with the aim of establishing easy-to-follow protocols.

METHOD : A retrospective study was conducted in children with DS who were seen at the paediatric genetic clinic at two academic hospitals. Data were collected from the hospital files and the results were extracted from the National Health Laboratory Service database system.

RESULTS : A total of 158 children were recruited; 25 children were excluded as they had had no thyroid function tests done. From the total of 133 included children, 70 (52.6%) were male. Babies born in one of the two hospitals numbered 60 (45.1%), whereas 54.9% were born in the other hospital. A total of 77 (57.9%) were found to have thyroid dysfunction; 55.8% of these patients were male. The most common thyroid abnormality was subclinical hypothyroidism in n=66/133 (49.6%), accounting for 85.7% of the causes of the thyroid dysfunction. Most children (n=45/133 (33.8%)) had their first thyroid function test done before the age of 2 months, followed by the age group of 1 - 5 years (n=34/133 (25.56%)). The total number of children started on treatment for their thyroid dysfunction was n=5/77 (6.49%).

CONCLUSION : Thyroid dysfunction is seen more commonly in children with DS compared with the general population, which was very evident in the present study. A standardised protocol will have a significant impact on the early management of these children, to prevent further cognitive impairment, especially in developing countries and at any level of healthcare. The recommendations for thyroid dysfunction screening by the American Academy of Pediatrics can be adjusted and tailored for the South African population. Early diagnosis and referral of children with DS to a secondary- or tertiary-level facility is of utmost benefit for these children for screening and treatment of comorbidities and complications.