NEUROPSYCHOLOGICAL DEVELOPMENT IN A CHILD WITH EARLY-TREATED CONGENITAL HYPOTHYROIDISM AS COMPARED WITH HER UNAFFECTED IDENTICAL TWIN

Objective: Neonatal screening for congenital hypothyroidism (CH) preve nts the serious neuropsychological features of CH, but the question re mains whether intelligence and motor skills of CH children treated ear ly are completely normal. Design: In this report we describe the rare case of two genetically identical twins, only one of whom was affected by CH due to thyroid agenesis. L-Thyroxine (9 mu g/kg body weight/day ) therapy was initiated al 27 days of age and was adequate throughout the follow-up. Methods: Neuropsychological evaluation was performed on the twins in parallel from 3 months to 8 years of age. Results: The C H twin (NB) did not show major neuromotor impairments but, compared wi th the unaffected twin (EB), she had a slight delay in postural/motor achievements and in language development that completely disappeared a t 8 years of age, On standardised tests of intelligence, NE was indist inguishable from control children but, compared with her twin, she had lower IQ scores in most testing occasions up to 7 years of age (NB = 108 vs EB = 115). School achievements of NE did not significantly diff er from those of her classmates but, compared with her twin, she score d worse in writing, mechanical reading, verbal memory, and possibly in arithmetic. Conclusions: Because the twins were genetically and pheno typically identical, were raised in the same environment, and received a similar education, it is concluded that hypothyroidism in utero and in the first neonatal month was responsible for the lower neuropsycho logical achievements of the CH twin. While foetal hypothyroidism is at present unavoidable, earlier diagnosis and initiation of treatment in neonates with CH are important and highly recommended.