[Etiologic diagnosis of congenital hypothyroidism and plasma thyroglobulin].

Plasma thyroglobulin (Tg) measurement at the time of screening has a great value in the classification of congenital thyroid defects. Tg was measured in a group of 100 children with congenital hypothyroidism (athyreosis n = 15, ectopic n = 59, eutopic n = 26). Tg was undetectable in athyreosis. These values were significantly different (2.46 +/- 2.52 ng/ml) from those in the group of ectopic (111 +/- 139 ng/ml) and in the group of eutopic (196 +/- 312.1 ng/ml). Four patients with eutopic glands had non measurable Tg and may represent cases with congenital Tg defect.