Subclinical hypothyroidism: treat or watch?

Manifest hypothyroidism occurs in more than 5 % of the population, while prevalence of subclinical hypothyroidism is much higher and reaches 15 %. In the practice of an endocrinologist, in most cases, the diagnosis and treatment of manifest hypothyroidism does not raise questions, while subclinical changes in thyroid hormones quite often generate a lot of discussions. The generally accepted reference range for TSH up to 4.50 μIU / ml is in conflict with data showing that more than 95 % of healthy people with euthyroidism have serum TSH levels up to 2.5 μIU / ml. At the same time, a lot of data has been accumulated on the effect of even slightly altered levels of thyroid hormones and TSH on various tissues, organs and systems of the body, especially on the cardiovascular, nervous and reproductive systems. This review analyzes the results of studies aimed at studying the relationship of subclinical hypothyroidism with cardiovascular and metabolic disorders, cognitive disorders, pathology of pregnant women.