الفهرس 
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Abstract
Subclinical thyroid disorders are clinically inapparent
disorders that are diagnosed by laboratory methods. Recent TSH
assays helped greatly in diagnosing such disorders.
Subclinical hypothyroidism (SCH) is defined as a persistently
elevated serum TSH levels with normal or low normal levels of
free T3 and T4 in the presence or absence of hypothyroid
symptoms. The high TSH levels in this condition reflects the
sensitivity of hypothalamo-pituitary axis to the small changes of
circulating thyroxine levels which may be at the low end of
normal.
The prevalence of SCH is about 4.3 to 9 % of general
population with much higher prevalence in women than men
especially older women. In addition there is a strong association
between positive thyroid peroxidase antibodies and elevated
TSH levels. Screening of SCH should be performed among high
risk groups including women older than 60 years, persons with
previous radiation treatment of the thyroid gland, those with
previous thyroid surgery or thyroid dysfunction, a family history
of thyroid disease, or AF and those who have type 1 diabetes
mellitus or a personal history of autoimmune disease.
The importance of SCH emerges from its clinical
implications. Some patients with SCH may have symptoms of
the overt disease such as dry skin, cold intolerance and easy
fatigability. These symptoms improve after treatment with
thyroid hormones.