Perinatal Goiter with Increased Iodine Uptake and Hypothyroidism due to Excess Maternal Iodine Ingestion

Abstract

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.

Congenital Hypothyroidism Caused by Excess Prenatal Maternal Iodine Ingestion

“…However, excess intrathyroidal iodine levels can cause a transient decrease in thyroid hormone production. This phenomenon is known as the acute Wolff-Chaikoff effect 3,6,7 and is in place to protect against overproduction of thyroid hormone due to iodine excess. In adults, an escape from the acute Wolff-Chaikoff effect usually occurs after a few days of exposure to excess iodine to protect against the development of hypothyroidism.…”

“…In Japan, where diets are high in iodine-rich seaweed, elevated iodine levels in maternal urine, serum, and breast milk samples have been shown to correlate with abnormal thyroid function in infants. 1 de Vasconcellos and Collett-Solberg 6 reported 8 cases of neonatal goiter thought to have developed as a result of maternal ingestion of a prenatal vitamin that was contaminated with excess iodine. Stagi et al 10 presented 2 neonates born with goiter and positive screening tests for CH whose mothers were later found to have taken an herbal supplement throughout their pregnancies high in iodine-containing alga kelp.…”

Conservatively Managed Fetal Goiter: An Alternative to in utero Therapy

“…Fetal goiter may arise from a variety of etiologies including iodine deficiency, overtreatment of maternal Graves' disease, inappropriate maternal thyroid replacement and, rarely, congenital hypothyroidism [1,2,3,4]. Congenital hypothyroidism is most often the result of thyroid gland dysgenesis and occurs on a sporadic basis.…”

Congenital Hypothyroidism due to Unexpected Iodine Sources

“…In conclusion, we are pleased that our colleagues have discussed this frequent We read with great interest the report of de Vasconcellos Thomas and CollettSolberg [1] about the review of cases of fetal/newborn goiter due to excess maternal iodine ingestion. The unknowing and wrong use of supplements represents an emerging problem in medical practice today because an increasing number of people believe that supplements are healthy and have no side effects [2,3] .…”