Neonatal TSH screening: is it a sensitive and reliable tool for monitoring iodine status in populations?

Area of Science:

• Endocrinology
• Public Health Nutrition
• Neonatal Medicine

Background:

• Iodine deficiency is a leading cause of preventable intellectual disability in newborns worldwide.
• Accurate assessment of iodine nutritional status is crucial for maternal and child health.
• Current methods for assessing iodine status include urinary iodine, thyroid size, and blood concentrations of thyroid stimulating hormone (TSH) and thyroglobulin (Tg).

Purpose of the Study:

• To evaluate the reliability of neonatal thyroid stimulating hormone (TSH) screening as an indicator of population iodine status.
• To assess the validity of World Health Organization (WHO) guidelines for using neonatal TSH to monitor iodine deficiency.

Main Methods:

• Review of studies utilizing neonatal TSH screening to determine population iodine sufficiency.
• Analysis of technical challenges and data variability associated with neonatal TSH measurements.
• Comparison of TSH-based iodine status assessment with established indicators.

Main Results:

• Many studies using neonatal TSH screening for iodine status assessment have yielded conflicting or uncertain data.
• Technical issues and unresolved challenges question the sensitivity and reliability of neonatal TSH as a quantitative tool for monitoring iodine status.
• The frequency of elevated neonatal TSH concentrations (>5 mIU/L) is not consistently indicative of iodine deficiency across populations.

Conclusions:

• Neonatal TSH screening presents significant technical challenges, making it an unreliable method for assessing population iodine status.
• Further research is needed to resolve technical issues before neonatal TSH screening can be reliably used for iodine deficiency monitoring.
• The WHO should reconsider its current guidelines on neonatal TSH screening for monitoring iodine deficiency due to its questionable reliability.