Perinatal goiter with increased iodine uptake and hypothyroidism due to excess maternal iodine ingestion.

Background/aims: To review cases of fetal/newborn goiter due to excess maternal iodine ingestion.

Methods: We reviewed the medical records of all patients that presented with congenital goiter in 2003. We used the PubMed search engine to conduct a review of publications addressing congenital goiter and excessive iodine intake.

Results: Maternal ingestion of large amounts of iodine due to an error in the manufacturing of a prenatal vitamin caused a goiter in her fetus. Seven other women who received the same prenatal vitamin had newborn children with goiters. Three of these children were hypothyroid at the time of initial examination. Three patients (2 hypothyroid and 1 euthyroid) had thyroid scans with radioactive iodine; iodine uptake was elevated (>80%) in all 3, and in 1 the perchlorate washout test was positive.

Conclusion: The finding of congenital goiter and increased iodine uptake in a newborn is considered diagnostic of dyshormonogenesis, a permanent form of hypothyroidism. Our description is important because it demonstrates that iodine excess during pregnancy may mimic some forms of dyshormonogenesis. The differentiation between the two causes of newborn goiter may prevent the lifelong use of supplemental levothyroxine in patients with a transient abnormality.