Thyroid disorders are amongst the most prevalent of medical conditions possibly after diabetes. The prevalence of thyroid dysfunction in adults in the general population ranges from 1 to 10 percent, and is even higher in selected groups. In the United Kingdom, 1–2% of the adult population is found to have thyroid dysfunction. It is interesting to note that thyroxin is the sixth most commonly dispensed drug in Scotland. Virtually all studies report higher prevalence rates for hypothyroidism in women and with advancing age.