Thyroid diseases and pregnancy

BACKGROUND Thyroid diseases and diabetes mellitus are the most common endocrine diseases during pregnancy. Internal Medicine doctors could be involved in the management of pregnant women affected by thyroid diseases, in particular if an Endocrine Unit lacks in the hospital; it is mandatory that they have the skills to cope with these diseases. METHODS In this work authors describe the most common thyroid abnormalities that can occur during pregnancy: hypothyroidism (clinical and subclinical), hyperthyroidism (clinical and sub-clinical), autoimmune thyroiditis (in particular the so called post-partum thyroiditis), nodular diseases and cancer. They discuss moreover the peculiar pathophysiologic mechanisms by which these diseases appear, the diagnostic tools and the therapies, according to their own experience and the more recent international guidelines. RESULTS AND CONCLUSIONS It is important to evaluate thyroid function tests before and during pregnancy, at 16th and 28th gestational week; it is mandatory to cure also the sub-clinical hypothyroidism during pregnancy, when TSH level are higher than 5 μIU/mL; the optimal dose of levo-thyroxine during pregnancy is, average, 30-50% higher than that used before pregnancy; it is not correct to treat mild or sub-clinical hyperthyroidism; propylthyouracil is the best drug to treat hyperthyroidism during pregnancy; the post-partum thyroiditis is generally transient, so that a careful monitoring of thyroid function is advisable, in particular after 9-12 months of therapy; thyroid cancer, if discovered during pregnancy, generally has no negative effects on the outcome of the pregnancy; it would be better to treat surgically thyroid cancer during the last trimester of the pregnancy.