The epidemiology of congenital hypothyroidism in the United Arab Emirates

Zayed, Reem (2006) The epidemiology of congenital hypothyroidism in the United Arab Emirates. Doctoral thesis, University of Central Lancashire.

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The newborn screening for congenital hypothyroidism (CR) started in the West in the sixties. The guidelines for screening were introduced in the majority of western countries some 30 years ago and were adapted in 1997 by the World Health
Organization. The United Arab Emirates (UAE) started newborn screening for CH in 1998 and was considered one of the leading countries in the Middle East to apply this programme nationwide. Before newborn screening for CH in the UAE, little was known about the epidemiology of the disease in this part of the world which shares the same epidemiological pattern of the Gulf region and the Middle East This nationwide study investigated the epidemiological pattern of CH in the UAE in terms of assessment of biological and environmental components and their significance in the relatively increased incidence of the disease in this community compared to the worldwide incidence (1:30004000). This study employed radioimmunoassay technique used by the newborn screening programme to measure the capillary Thyroid Stimulating Hormone (TSR) for all newborns at the week of age. In addition, chemical and radiological techniques were employed to screen for positive cases.
Firstly, cases detected have been studied in terms of prevalence of the disease in the UAE in relation to other parts of the world and the definition of the epidemiological components and its association to the prevalence of the disease. The study included the investigation of the genotypic pattern of congenital hypothyroidism in the UAE among certain cases with familial dyshormonogesis phenotype. The results show high incidence of the disease compared to the worldwide incidence and also it showed a specific epidemiological pattern. Secondly, the study employed the data obtained in newborn screening for CH in a longitudinal study of TSR pattern of the population and its use to monitor the iodine uptake of this population. This part of study also studied other important implications of the TSR pattern which included the TSR surge and the prevalence of sub clinical cases in which TSH is the main monitor.Thirdly, the study evaluated the controversial issues in the newborn screening programme in the preanalytic and post-analytic phases of the programme. The role of incorporation of the pre and post analytical quality control of the programme in reduction of the morbidity of the disease. Nevertheless, this study provides an overview for the epidemiological pattern of congenital hypothyroidism in the UAE and forms a basic epidemiologic background for further detailed studies that would focus on the clinical aspect and prognostic outcome of the disease. It may be concluded that the clinical picture of congenital hypothyroidism has changed dramatically since newborn screening was instituted in the UAE. Population-based registers and linked-databases can provide very useful information for evaluating screening programmes, and extending current knowledge of the epidemiology of congenital hypothyroidism. This is the first epidemiological study of CH in the UAE in which data from population-based registries were linked, the epidemiologic patterns and associated factors are more representative. The study delineates the significantly increased incidence of congenital hypothyroidism compared to the universal incidence and the clear correlation of this incidence with certain risk
factors. Some of these are local which pertain to this area of the world and end in constituting this specific epidemiological pattern.

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