Context: Central congenital hypothyroidism (CH-C) in neonates born to mothers with inadequately treated Graves' disease usually needs T4-supplementation. The thyroid and its regulatory system have not yet been extensively studied after T4-withdrawal, until we observed disintegrated thyroid glands in some patients.

Objective: To study the occurrence and pathogenesis of disintegrated thyroid glands in CH-C patients.

Design/Setting/Patients/Participants: Thyroid function was measured and thyroid ultrasound imaging performed in 13 children with CH-C due to inadequately treated maternal Graves' disease after T4-supplementation withdrawal (group Aa). In addition, thyroid ultrasound imaging was done in 6 children with CH-C born to inadequately treated mothers with Graves' disease, in whom T4-supplementation was not withdrawn yet (group Ab) or never initiated (group Ac), in 6 euthyroid children born to adequately treated mothers with Graves' disease (group B) and in 10 T4-supplemented children with CH-C as part of multiple-pituitary-hormone-deficiency (group C).

Main Outcome Measure: Thyroid function and aspect (volume, echogenicity, echotexture).

Results: In group A 5 children had developed thyroidal hypothyroidism characterized by persistently elevated TSH-concentrations and exaggerated TSH-responses after TRH-stimulation. In the majority of patients of group A and C thyroid echogenicity and volume was decreased and echotexture inhomogeneous. Thyroid ultrasound imaging was normal in group B children.

Conclusion: Inadequately treated maternal Graves' disease may not only lead to CH-C but also carries an, until now, unrecognized risk of thyroid disintegration in the offspring as well. We speculate that insufficient TSH-secretion due to excessive maternal-fetal thyroid hormone transfer inhibits physiological growth and development of the child's thyroid.