Perinatal exposure to excess Iodine can lead to transient hypothyroidism in the newborn. In Japan, large quantities of iodine-rich seaweed such as kombu (Laminaria japonica) are consumed. However, effects of Iodine from food consumed during the perinatal period are unknown. The concentration of Iodine in serum, urine, and breast milk in addition to thyrotropin (TSH), free thyroxine (FT4), and thyroglobulin was measured in 34 infants who were positive at congenital hypothyroidism screening. Based on the concentration of iodine in the urine, 15 infants were diagnosed with hyperthyrotropinemia caused by the excess ingestion of iodine by their mothers during their pregnancy. According to serum iodine concentrations, these infants were classified into group A (over 17 µg/dL) and group B (under 17 µg/dL) of serum iodine. During their pregnancies these mothers consumed kombu, other seaweeds, and instant kombu soups containing a high level of iodine. It was calculated that the mothers of group A infants ingested approximately 2300–3200 µg of iodine, and the mothers of group B infants approximately 820–1400 µg of iodine per day during their pregnancies. Twelve of 15 infants have required levo-thyroxine (LT4) because hypothyroxinemia or persistent hyperthyrotropinemia was present. In addition, consumption of iodine by the postnatal child and susceptibility to the inhibitory effect of iodine may contribute in part to the persistent hyperthyrotropinemia. We propose that hyperthyrotropinemia related to excessive iodine ingestion by the mother during pregnancy in some cases may not be transient.
The Germans loved to scrub up with their Betadine:
Abstract Transient hyperthyrotropinemia and/or hypothyroidism have been found in many newborn infants during thyroid screening programs. In Europe the most likely causes are iodine deficiency and iodine overload. Because of the high incidence of transient hyperthyrotropinemia in Berlin we measured iodine concentrations in casual urine samples of newborns with TSH elevations. Urine and blood samples were collected on the 5th day of life. In the prospective study 99 out of 9320 newborns (1.06%) displayed TSH concentrations ranging from 20 to 152 mgrU/ml. All infants had normal TSH levels during a control examination. The urinary iodine concentrations were significantly elevated in 76 out of the 99 newborns. Most of the patients were born in obstetric departments where iodine-containing antiseptic agents were routinely used for disinfection during labor. The use of iodine-containing antiseptic agents not only results in unnecessary control determinations for the thyroid screening program but also causes an undesirable metabolic situtation that may be a potential hazard for the development of the central nervous system.