Neonatal thyroid disease: differential expression in three successive offspring.

Neonatal thyroid disease, manifested as either hyperthyroidism or hypothyroidism, has been described in the offspring of women with autoimmune thyroid disorders. We report clinical and laboratory observations in a mother with autoimmune thyroiditis who gave birth to three children with different forms of thyroid dysfunction. The first child was clinically normal, the second child had transient neonatal hyperthyroidism, and the third child had neonatal hypothyroidism. After the birth of the second child, the mother was found to be biochemically hypothyroid. Long-acting thyroid stimulator and antithyroid microsomal antibodies were detected in her serum. She was treated with L-T4 (0.15 mg/day). After the birth of her third child, the mother was found to have thyroid-stimulating immunoglobulins and TSH-blocking inhibitory immunoglobulins in her serum. The latter also were detected in the third newborn. Six weeks later, TSH-blocking inhibitory immunoglobulins were not detected in the child, but they persisted in the mother. This report further expands the spectrum of neonatal thyroid disease and suggests that differing disease syndromes in the newborn can occur depending on whether stimulating or blocking antibodies predominate in the mother.