Question

• 2 year old female is being evaluated in Peds Endocrinology Clinic for her early-treated congenital hypothyroidism (CH). Is she at increased risk for developmental difficulties even though treated early?

Clinical Bottom Lines

1. Early-treated congenital hypothyroid children do not have increased risk of severe learning disabilities.¹
2. Subtle deficits are more apparent at early school age and some of these deficits may improve over time.
3. However, with lower school performance found at later school age, this may indicate emerging difficulty with complex skills needed for subjects such as science.
4. Some deficits may be attributable to sensorineural hearing loss associated with poor cochlear development, so hearing screening is important in these patients.
5. Both severity of congenital hypothyroidism at presentation and increased doses of thyroid hormone can put these children at risk for ADD-like problems, necessitating close monitoring and tight control of replacement therapy throughout childhood.

Summary of Key Evidence

1. Children with CH had a higher risk for generalized learning disability (23% versus the 13%) compared to matched sibling and classmate controls.¹
2. Children with CH had lower full-scale IQs in grade 3 than controls (105 vs. 112).
3. Parents and teachers of CH children rated them higher in behavior problems than controls.
4. In grade six, the learning disabilities, IQ, and behavioral differences were no longer present between controls and CH patients.
5. Teachers rated CH patients tested in both grades as poorer school performers in grade 6 than 3, even though other differences had disappeared by then.

Additional Comments

• Newborn screening for Hypothyroidism & PKU is required by law in all 50 states.²
• Congenital hypothyroidism affects 1 in 3500 children worldwide. The incidence is higher in Hispanics and Native Americans than Caucasians and African Americans.
• Congenital Hypothyroidism, if left untreated, causes growth retardation and irreversible mental retardation because thyroid hormones are necessary for fetal and early childhood brain development.

Citation

1. Rovet JF, Ehrlich R. Psychoeducational outcome in children with early-treated congenital hypothyroidism. Pediatrics. 2000;105:515-522.
2. Pass KA, et al. US newborn screening guildelines II: Followup of children, diagnosis, management, and evaluation. Journal of Pediatrics. 2000; 137: S1-46.

CAT Author: Michelle Viglianco-VanPelt, M.D.

CAT Appraisers: John Frohna, MD

Date appraised: August 27, 2001