Neonatal Thyroid-Stimulating Hormone Screening as a Monitoring Tool for Iodine Deficiency in Turkey

Area of Science:

• Endocrinology
• Public Health
• Pediatrics

Background:

• Thyroid-stimulating hormone (TSH) levels in newborns serve as a key indicator for assessing population-level iodine deficiency (ID) and monitoring iodine supplementation programs.
• The National Newborn Screening Program (NNSP) for congenital hypothyroidism (CH) collects crucial data for public health surveillance.

Purpose of the Study:

• To analyze neonatal TSH levels from the 2014 NNSP data to predict the current iodine nutrition status in Turkey.
• To identify regional and seasonal variations in elevated TSH levels as indicators of potential iodine deficiency.

Main Methods:

• Utilized heel-prick blood samples from newborns collected on filter paper cards, analyzing results from samples obtained >48 hours post-birth.
• Assessed the severity of iodine deficiency using World Health Organization (WHO) epidemiologic criteria.
• Classified elevated TSH levels (>5 mIU/L) based on province, region, birth season, and sampling time.

Main Results:

• A total of 1,270,311 newborns' screening results were included in the analysis.
• The national prevalence of elevated TSH was 7.2%.
• Significant regional variations were observed, with the highest TSH elevation rate in Gaziantep (15.9%) and the lowest in Tekirdağ (4.0%). Seasonal analysis showed the highest prevalence in winter (7.4%).

Conclusions:

• Neonatal CH screening results suggest that Turkey may be experiencing mild iodine deficiency.
• Further nationwide studies are essential for a direct assessment and accurate monitoring of iodine status in vulnerable populations.