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Skeletal maturation during thyroxine treatment in children with congenital hypothyroidism
S Heyerdahl1, B F Kase, G Stake
1Department of Pediatric Research, Rikshospitalet, Oslo, Norway.
Insights
Early L-thyroxine treatment for congenital hypothyroidism shows a slight delay in bone age development. Higher L-thyroxine doses and serum thyroxine levels in the first year correlate with improved bone age, supporting its use in monitoring treatment.
Area of Science:
- Pediatric Endocrinology
- Skeletal Maturation
- Congenital Hypothyroidism Management
Background:
- Congenital hypothyroidism (CH) requires timely L-thyroxine replacement therapy.
- Skeletal maturation can be delayed at diagnosis in CH patients.
- The impact of early treatment on bone age development needs further elucidation.
Purpose of the Study:
- To investigate the relationship between bone age development and L-thyroxine treatment in children with CH.
- To assess the influence of L-thyroxine dosage and serum thyroxine levels on bone age in early-treated CH.
- To evaluate the utility of bone age assessment in monitoring CH treatment.
Main Methods:
- Retrospective study of 47 children diagnosed with CH and treated early.
- Bone age assessed using the Greulich & Pyle atlas.
- Correlation analysis between bone age, L-thyroxine dose (mcg/kg/day), and serum thyroxine levels (nmol/l) during the first year of life.
Main Results:
- Despite initial delays, mean bone age at 1.5 years showed only a slight delay (0.5 months).
- L-thyroxine dose and serum thyroxine levels in the first year accounted for 30% of the variation in bone age SD score at 1.5 years.
- Children with bone age within +/- 1 SDS received a mean L-thyroxine dose of 5.4 +/- 1.7 mcg/kg/day and had mean serum thyroxine of 175 +/- 29 nmol/l.
Conclusions:
- Bone age at 1.5 years positively correlates with L-thyroxine dose and serum thyroxine concentrations in the first year.
- Bone age assessment can serve as a valuable complementary tool alongside other variables for monitoring CH treatment.
- Early and appropriate L-thyroxine therapy appears to normalize skeletal maturation over time.
Abstract:
The aim of this investigation was to study if bone age development (assessed by the Greulich & Pyle atlas) was related to L-thyroxine treatment in 47 children with congenital hypothyroidism, treated early and according to general recommendations. In spite of frequent delay in skeletal maturation at diagnosis, the delay in mean bone age at a mean chronological age of 1.5 years was slight (0.5 months), and 30% of the variation in bone age SD score (SDS) at 1.5 years was accounted for by the dose of L-thyroxine and serum thyroxine during the first year. The children with a bone age within +/- 1 SDS had a prescribed mean dose of L-thyroxine per kg body weight from 3 to 12 months of age of 5.4 +/- 1.7 micrograms/kg/day, and their mean serum thyroxine concentration during the first year was 175 +/- 29 nmol/l. We conclude that bone age at 1.5 years of age was positively correlated with the dose of L-thyroxine and the serum thyroxine concentrations during the first year. This supports the general use of bone age assessments as a complement to other treatment variables in the follow-up of children with congenital hypothyroidism.