Serum TSH testing is necessary for primary hypothyroidism case finding.(Expert's Comments)(thyrotropin )

Hypothyroidism is the most common functional disorder of the thyroid gland. Pathology of the thyroid gland (primary hypothyroidism) accounts for over 99.5% of cases of thyroid gland failure and < 0.5% result from disorders of the pituitary gland or hypothalamus (central hypothyroidism). Overt primary hypothyroidism refers to cases in which the serum thyrotropin (TSH) concentration is elevated and the serum free thyroxine (T4) level is below the reference range, while subclinical hypothyroidism is defined as an elevated serum TSH value associated with a serum free T4 that is still within the reference range.

The incidence of overt hypothyroidism has been estimated to be 4.1 cases per 1000 women per year and 0.6 cases per 1000 men per year. (1) The prevalence has been reported to be approximately 1-2% in women and 0.1% in men in large population studies. (2-4) The prevalence of subclinical hypothyroidism is far higher, having been reported to be about 4-10% in multiple populations (4-6) and as high as 18% in the elderly? (4-8)

Symptoms and signs …