Incidence of iodine contamination in neonatal transient hyperthyrotropinemia.

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 microU/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 situation that may be a potential hazard for the development of the central nervous system.