Objective: To assess the differences in the blood concentration levels of the thyroid stimulating hormone and their possible use as an indicator of iodine sufficiency, in a sample of Mexican newborns.
Material and methods: A cross-sectional study was conducted from September 1999 to August 2000, among 25,427 Mexican newborns in the Ministry of Health clinics from 5 states. A total of 8,095 heel-prick and 17,332 umbilical cord blood samples were analyzed. Blood samples were collected in filter paper and processed by enzyme-linked immunosorbent assay. The Mann-Whitney U test and the Kruskal-Wallis test were used for statistical analyses.
Results: Hyperthyrotropinemia was found in 9.95% of heel samples and in 24.27% of umbilical cord samples (TSH > 5 microUl/ml).
Conclusions: The percentage of hyperthyrotropinemia observed in this study was higher than that expected in a population with sufficient iodine intake; these findings could be due to poor maternal iodine intake.