Background: An important issue in the management of congenital hypothyroidism (CH) is the best initial dose of levothyroxine (L-T4) in order to achieve optimal neurocognitive outcomes. Both European and American guidelines suggest an initial dose of 1015 μg/kg per die but trials on long-term effects of different doses within this range are lacking.
Objective and hypotheses: This was a multicenter randomized trial to evaluate the effects of the initial dose of L-T4 on growth and neurodevelopmental outcomes in children with CH.
Method: Seventy-two children with CH diagnosed by neonatal screening were enrolled in the study. They were randomly assigned to receive an initial L-T4 dose of 1012.5 μg/kg per die (group A) or 12.615 μg/kg per die (group B). All patients underwent clinical examination and FT4 and TSH measurement after 710 days of treatment and at the age of 1.5, 3, 6, 9 and 12 months. At the age of 12 months they underwent Griffiths Mental Development Scales to evaluate cognitive development. Four patients were lost to the follow-up and two patients have not yet reached 12 months of age; therefore only 66 children (32 from group A and 34 from group B) concluded the first year of study.
Results: No significant differences were detected in auxological parameters between the two groups (Table 1).
The intelligent quotient (IQ) at 12 months of age was similar in the two groups (104.79±13.18 vs 104.77±12.81). IQ correlated with age at diagnosis (r=−0.03, P=0.02) and FT4 levels after 710 days of L-T4 therapy (r=0.33, P=0.01).
|3 months||6 months||9 months||12 months|
Conclusion: Different initial doses of L-T4 within the range of 1015 μg/kg per die provide similar outcomes in growth and neurocognitive development in CH patients.
01 - 03 Oct 2015
European Society for Paediatric Endocrinology