Subclinical Hypothyroidism

Subclinical hypothyroidism (SCH) is a biochemical condition characterized by high serum thyroid stimulating hormone (TSH), with normal levels of thyroid hormones and without overt clinical features of hypothyroidism.
Thyroxine replacement therapy is reasonable for patients with a TSH greater than 10 mU/L because the rate of progression to overt hypothyroidism is up to 5% per year in comparison with lower TSH levels.
For patients with a mild degree of SCH (TSH ≤ 10 mU/L) thyroxine replacement therapy is recommended if they have symptoms, goiter, anti-TPO antibodies or infertility and in pregnant patients.
This review discusses the risks and/or benefits of thyroxine replacement treatment of subclinical hypothyroidism for those patients with a serum TSH level of 4.5-10.0 mIU/L.

Keywords: Subclinical hypothyroidism, Thyroid stimulating hormone, Cardiovascular risk, Cognition, Thyroxine replacement.