[Clinical guideline for the diagnosis and treatment of subclinical thyroid dysfunction in pregnancy. Working Group on Subclinical Thyroid Dysfunction of the Spanish Endocrinology Society].

Subclinical thyroid disease is a biochemical diagnosis and is common during pregnancy. Because of the physiological hormonal changes that take place during pregnancy and the absence of normal ranges for thyroid hormones during this period, subclinical thyroid disease is difficult to interpret during pregnancy. Subclinical hyperthyroidism during pregnancy has few clinical consequences and no treatment is required. In contrast, subclinical hypothyroidism seems to improve with thyroxine treatment. Iodine supplements during pregnancy and lactation, even in iodine-sufficient areas, are also indicated.