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Congenital hypothyroidism occurs in approximately
1/3,500-4,000 live births and screening programmes for congenital
hypothyroidism are well established worldwide. They usually take
place at birth or within five days in combination with screening
for phenylketonuria. Prompt treatment with thyroxine of
individuals with inappropriately raised TSH and/or low total T4
has effectively eliminated mental retardation resulting from
congenital hypothyroidism and the programmes are deemed to be
cost effective and are well organised.
The question of whether or not adults should be screened for thyroid disease is a matter for debate (5,6). The prevalence of unsuspected overt thyroid failure and thyrotoxicosis in men is so low that it would not be cost effective to screen men. The frequency and natural history of thyrotoxicosis is such that it is likely to be detected in women at a relatively early stage in the natural history. Screening women in pregnancy for thyroid antibodies has been advocated as a means of detecting those who are at risk of developing post partum thyroiditis but the cost benefit of this has not been proven. Screening women in the community with a TSH assay and thyroid antibodies will detect a significant proportion of subjects with incipient thyroid failure, ranging between 5%-10% of women around the age of 50. It is important to remember this particularly when women present with symptoms attributed to the menopause and other elderly women with non-specific symptoms often simply attributed to age. It is important to exclude hypothyroidism in such individuals. If a TSH is found to be elevated then a trial of thyroxine is justified to determine whether or not the symptoms are relieved over a period of three months. The cost effectiveness of screening for mild thyroid failure at a periodic health examination has been evaluated and is thought to be reasonable and cost-effective practice when compared with other widely accepted preventive medical interventions for women over the age of 35 (7). This still raises questions as to how frequently such tests should be conducted and the answer is probably not more often than every five years. |
