Neonatal screening for congenital hypothyroidism in The Netherlands: Cognitive and motor outcome at 10 years of age

Context: Patients with thyroidal congenital hypothyroidism (CH-T) born in The Netherlands in 1981-1982 showed persistent intellectual and motor deficits during childhood and adulthood, despite initiation of T₄ supplementation at a median age of 28 d after birth. Objective: The present study examined whether advancement of treatment initiation to 20 d had resulted in improved cognitive and motor outcome. Design/Setting/Patients: In 82 Dutch CH-T patients, born in 1992 to 1993 and treated at a median age of 20 d (mean, 22 d; range, 2-73 d), cognitive and motor outcome was assessed (mean age, 10.5 yr; range, 9.6-11.4 yr). Severity of CH-T was classified according to pretreatment free T₄ concentration. Main Outcome Measure: Cognitive and motor outcome of the 1992-1993 cohort in comparison to the 1981 to 1982 cohort was the main outcome measure. Results: Patients with severe CH-T had lower full-scale (93.7), verbal (94.9), and performance (93.9) IQ scores than the normative population (P < 0.05), whereas IQ scores of patients with moderate and mild CH-T were comparable to those of the normative population. In all three severity subgroups, significant motor problems were observed, most pronounced in the severe CH-T group. No correlations were found between starting day of treatment and IQ or motor outcome. Conclusions: Essentially, findings from the 1992-1993 cohort were similar to those of the 1981-1982 cohort. Apparently, advancing initiation of T₄ supplementation from 28 to 20 d after birth did not result in improved cognitive or motor outcome in CH-T patients.