ABSTRACT
A long-standing association between Down syndrome (DS) and thyroid disorders has been well documented in the literature. The relationship between dementia and thyroid dysfunction in Alzheimer's disease (AD) in the general population has for many years been the focus of considerable clinical and research interest. Thyroid dysfunction may occur at any age. It should be treated in the earliest possible stages, when it is reversible. The thyroid gland is located at the base of the throat. It is butterfly-shaped and weighs 15–25 g, the right lobe being larger than the left. It is composed of many follicles which contain colloid surrounded by a single layer of epithelium. Thyroid function is dependent upon the availability of iodine and several other trace elements. The relationship between the iodine intake level of a population and the occurrence of thyroid diseases is U-shaped, with an increase in risk associated with both low and high iodine intake.
