Incidence Thyroid hormone deficiency may: or acqulre d Congenital: most cases are hypoplasia or aplasia of the thyroid gland World:1:3000~5000 China: 1: 3 200Incidence • Thyroid hormone deficiency may: or acquired • Congenital:most cases are hypoplasia or aplasia of the thyroid gland World: 1:3 000～5 000 China: 1:3 200