Influence of Timing and Dose of Thyroid Hormone Replacement on Mental, Psychomotor, and Behavioral Development in Children with Congenital Hypothyroidism

Our study suggests that initial and postinitial suboptimal treatment of CH leads to abnormalities in IQ and specific fields. Overtreatment may advance cognitive development in 5-1/2- to 7-year-olds. Suboptimal initial treatment may lead to behavioral problems. We recommend that TSH concentrations be maintained within the normal range in patients with CH.