Efficacy of oral iodide therapy on neonatal hyperthyroidism caused by maternal Graves' disease

To verify the efficacy of oral iodide therapy in treating a case of early neonatal hyperthyroidism due to maternal Graves' disease.

We report a case of neonatal hyperthyroidism which occurred in a 2,650-gram, female baby, born at 39 weeks' gestational age (GA) to a 30-year-old mother affected by Graves' disease and treated with thionamides (propylthiouracil) from the 20th week of gestation. A fetal goiter, due to maternal therapy, had been observed by ultrasound scan at 31 and 35 weeks of gestation, with contemporary low cord thyroid hormone levels. Two intra-amniotic injections of levothyroxine were then performed at 34 and 36 weeks of gestation, which led to a significant reduction of fetal goiter and to normalization of cord thyroid hormone levels. The neonatal clinical course was characterized by symptoms of hyperthyroidism from the 2nd to 3rd days of life (irritability, tachycardia, tachypnea, hyperphagia), mostly during feeding. Oral treatment with potassium iodide (KI, 8 mg x 3 times a day) was started at 23 days of life.

Treatment with KI led to a significant reduction of neonatal clinical symptoms and to a normalization of hormone levels within 4 days of therapy. The treatment was discontinued in 13th week of life because of neonatal well-being and normal hormone levels.

We believe that KI therapy is effective in treating neonatal hyperthyroidism and does not cause suppression of neonatal thyroid activity, which is possible using antithyroid drugs like thionamides.