Women with Autoimmune Thyroiditis Taking Levothyroxine During Pregnancy: Is Iodine Supplementation Needed?

Background: Iodine is fundamental for the synthesis of thyroid hormones, which play a central role in foetal neurological development. The need for an iodine-containing supplement (ICS) in L-T4-treated women during pregnancy is still a subject of debate. Aim of the Study: The aim of the study is to investigate the iodine status in women with autoimmune thyroiditis (AT) who have or have not been treated with L-T4. Methods: This was a cross-sectional, observational study involving pregnant women with AT, treated with/without L-T4. Upon enrolment, women provided a urine sample (to measure the urinary iodine concentration (UIC), which was normalised to urinary creatinine values (UI/Creat)), and completed a questionnaire. TSH, FT4, and neonatal TSH were also obtained. Results: Among women taking an ICS, 74.1% had a UI/Creat level ≥ 150 μg/g, compared with only 46.2% of those not taking an ICS (p = 0.03). Among L-T4 users only, a UI/Creat level ≥ 150 μg/g was more frequent in ICS users than ...