Bone age at birth; method and effect of hypothyroidism

Area of Science:

• Pediatrics
• Endocrinology
• Radiology

Background:

• Bone maturity in newborns is crucial for assessing neonatal health and thyroid function.
• Congenital hypothyroidism (CHT) leads to retarded bone maturation, indicating prenatal thyroid deficiency severity.
• Distal femoral epiphyses (FE) ossification is a key indicator of neonatal bone age.

Purpose of the Study:

• To establish a reliable method for estimating neonatal bone age in infants.
• To address the confounding effect of body size on distal femoral epiphyses (FE) height measurements.
• To validate the use of FE height lag as an indicator of bone maturation, particularly in congenital hypothyroidism.

Main Methods:

• Utilized a reference group of 111 healthy infants to develop predictive models for FE height (FEH) using multiple linear regression.
• Confirmed predictive models in a separate group of 37 healthy infants.
• Calculated FE height lag by comparing observed FEH to predicted FEH to account for age and body size variations.

Main Results:

• Infant body size was identified as a confounder when estimating bone age solely from FE size.
• FE height (FEH) and FE height lag were found to correlate with serum thyroxine concentrations in 52 hypothyroid newborns.
• FE height lag proved to be a more accurate indicator of bone maturation than FEH alone in heterogeneous populations.

Conclusions:

• FE height lag is a superior method for assessing bone maturation in infants, especially when age and body size vary.
• This method provides a reliable measure of bone maturation and can be used to assess the severity of prenatal thyroid failure in congenital hypothyroidism.
• FE height lag offers a valuable tool for pediatric endocrinologists and neonatologists in evaluating infant development and thyroid status.