title: Controversies in endocrinology: On the need for universal thyroid screening in pregnant women.
abstract: There is a well-known controversy among scientific societies regarding the recommendation to screen for thyroid dysfunction (TD) during pregnancy. Although several studies have shown an association between maternal subclinical hypothyroidism and/or hypothyroxinemia with obstetric problems and/or neurocognitive impairment in the offspring, there is only limited evidence on the possible positive effects of thyroxine (T4) treatment in such cases. Despite the scarcity of this evidence, there is a widespread agreement among clinicians on the need for treatment of clinical hypothyroidism during pregnancy and the risks that could arise due to therapeutic abstention. As maternal TD is a quite prevalent condition, easily diagnosed and for which an effective and safe treatment is available, some scientific societies have proposed to assess thyroid function during the first trimester of pregnancy and ideally before week 10 of gestational age. Given the physiologic changes of thyroid function during pregnancy, hormone assessment should be performed using trimester-specific reference values ideally based on locally generated data as geographic variations have been detected. Screening of TD should be based on an initial determination of TSH performed early during the first trimester and only if abnormal should it be followed by either a free or total T4 measurement. Furthermore, adequate iodine supplementation during pregnancy is critical and if feasible it should be initiated before the woman attempts to conceive.
authors.affiliation: Department of Endocrinology and Nutrition, Hospital de Sant Joan Despí Moisès Broggi, Barcelona, Spain.
authors.forename: Lluís
authors.initials: L
authors.lastname: Vila
authors.forename: Inés
authors.initials: I
authors.lastname: Velasco
authors.forename: Stella
authors.initials: S
authors.lastname: González
authors.forename: Francisco
authors.initials: F
authors.lastname: Morales
authors.forename: Emilia
authors.initials: E
authors.lastname: Sánchez
authors.forename: Sara
authors.initials: S
authors.lastname: Torrejón
authors.forename: Berta
authors.initials: B
authors.lastname: Soldevila
authors.forename: Alex
authors.initials: A
authors.lastname: Stagnaro-Green
authors.forename: Manuel
authors.initials: M
authors.lastname: Puig-Domingo
mesh_terms: D000328:Adult; D019317:Evidence-Based Medicine; D005260:Female; D006291:Health Policy; D020249:Hormone Replacement Therapy / Q000009:adverse effects; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D062145:Maternal Serum Screening Tests; D017410:Practice Guidelines as Topic; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis; D013961:Thyroid Gland / Q000503:physiopathology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use
chemical_list: D013972:Thyrotropin; D013974:Thyroxine