The effects of mild iodine deficiency on neonatal thyroid function

Area of Science:

• Endocrinology
• Neonatal Health
• Public Health

Background:

• Endemic goitre areas in Greece previously showed adults with low thyroxine (T4) and normal thyroid-stimulating hormone (TSH).
• This pattern in adults was hypothesized to be due to increased serum triiodothyronine (T3) levels.
• Neonatal thyroid function in these iodine-deficient regions remained under-investigated.

Purpose of the Study:

• To assess neonatal thyroid function in iodine-deficient goitre areas of Greece.
• To compare thyroid hormone levels in neonates from endemic versus non-endemic regions.
• To understand the implications of neonatal thyroid dysfunction for public health initiatives.

Main Methods:

• Measurement of T4 and TSH levels in dried blood spots from 259 neonates.
• Comparison of thyroid function parameters between full-term neonates from endemic villages, non-endemic villages, and Athens.
• Inclusion of premature neonates from both endemic and non-endemic areas for comparative analysis.

Main Results:

• Full-term neonates from endemic villages exhibited significantly lower T4 and higher TSH levels compared to those from non-endemic villages and Athens.
• Premature neonates, irrespective of region, showed lower T4 and TSH values than full-term neonates, attributed to pituitary-thyroidal axis immaturity.
• Findings suggest neonates are more susceptible to iodine deficiency consequences than adults.

Conclusions:

• Neonates in iodine-deficient areas experience biochemical hypothyroidism, potentially linked to delayed skeletal maturation.
• Correcting even moderate iodine deficiency is crucial for neonatal development.
• The study suggests increased TSH stimulation during neonatal life is key for goitre formation, not adult maintenance.
• Newborn screening programs in endemic areas must consider these specific neonatal thyroid function findings.