Subclinical Hypothyroidism

Ubclinical hypothyroidism (sch) is defined as a normal serum ff4 and ahigh serum thyrotropin (tsh) concentration.up to 30% of patients with sch may have vague, non-specificsymptoms of hypothyroidism, but attempts to identify the patients on the basis of clinical finding have not been successful, so the diagnosiscan only be made with laboratory testing.the causes of sch are the same as those of overt hypothyroidism. most patients have hashimoto's thyroiditis. the worldwide prevalenceof sch ranges from 1-10%. a substantial proportion of patients with sch develop overt hypothyroidism. serum tsh concentration andpositive antithyroid antibodies (ata) are significant predictors of progression to clinical hypothyroidism.some patients with sch have some symptoms of hypothyroidism, while some studies show significant improvement in hypothyroidsymptom scores and psychometric testing; others found no improvement in symptoms with levothy roxine therapy.there is consensus that sch in pregnancy is a risk factor for poor developmental outcomes inthe offspring and the condition should betreated in women who wish to become pregnant. there is also agreement that patients with sch and tsh levels over 10 mull, or with goiter should be treated. population-based screening for sch is not warranted, but thyroid function should be tested in high risk groups, e.g. in women aged over 60 yr, persons with previous radiation therapy of thyroid gland or external.radiation, those with previous thyroid surgery ofthyroid dysfunction, type 1 diabetes mellitus patients and those with a family history of autoimmune disease. evidence documenting routinedetermination of tsh in pregnant women or women planning to become pregnant are insufficient, and it would be reasonable to considertsh measurement in those at high risk for thyroid dysfunction.