M.Med. (Medical Genetics)--University of the Witwatersrand, Faculty of Health Sciences, School of Pathology, 2012 / Down syndrome (DS) (OMIM #190685), the most common viable chromosome
abnormality, is associated with an increased risk of medical complications. The most
frequent endocrine abnormalities observed in children with DS involve the thyroid gland,
and the risk of thyroid dysfunction increases with age. Global studies have documented a
wide spectrum of thyroid dysfunction in children with DS.
Due to the paucity of data from sub-Saharan Africa regarding thyroid function in African
children with DS, this study was conceived. The main aim of the study was to document
the range of thyroid function in a cohort of 391 South African children with DS, seen at the
Genetic Clinics from 2003 to 2008. Referral and treatment practices at two tertiary
hospitals in Johannesburg were also documented. The majority (84%) of children had at
least one thyroid function test (TFT) performed, and the most common form of thyroid
dysfunction encountered was subclinical hypothyroidism (25.3%). Notably, up to one
third of patients with abnormal TFT results were not referred to the Endocrine Clinics for
evaluation, and were thus not receiving the necessary treatment. There were 13 neonates
with congenital hypothyroidism; at least two of them were not referred, and thus not
treated during the sensitive neonatal period.
A significant difference was noted between the results from Chris Hani Baragwanath
Hospital and those from the other two hospitals. The difficulties in interpretation of results
obtained from different biochemical machines and different populations, as compared to
those used to derive the reference ranges, were raised. Problems with regular follow-up of
patients and annual thyroid surveillance were also highlighted.
The clinical features of hypothyroidism may be difficult to distinguish from the phenotypic
features of DS. Thus, regular biochemical screening, even in the absence of physical signs
and symptoms, is warranted in this group of children to ensure that hypothyroidism is
treated, and further, irreversible neurological and physical impairment prevented.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/12608 |
| Date | 28 March 2013 |
| Creators | Moosa, Shahida |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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