Clinical courses and thyroid conditions in three infants born to a mother with thyroid stimulating-blocking antibodies.

The clinical courses including thyroid conditions of three infants born to a mother with primary hypothyroidism due to Hashimoto's thyroiditis were studied. The mother was positive for both TSH-binding inhibitor immunoglobulins (TBII) and thyroid stimulating-blocking antibodies (TSBAb) in her serum. The first infant died because of septic shock due to fistula formation between the large intestine and the bladder. Serum thyroid hormone levels during the first pregnancy were extremely low because of incomplete replacement therapy with levothyroxine. The second infant had almost normal thyroid function, so that the replacement therapy was not necessary. The third infant had transient and overt primary hypothyroidism. The replacement therapy was carried out for six months after birth. TSBAb activities in this mother were high in the third pregnancy. In general, these activities gradually increases with the clinical course in TSBAb-positive Hashimoto's patients. From these findings, it was suspected that the thyroid conditions in the second and the third infants reflected the natural course of TSBAb activities in this mother.