Neonatal Thyrotropinemia (tsh) as an Indicator of Iodine Nutritional Level in Castellon and Valencia, Spain (2004-2006

Abstract

Background: In the congenital hypothyroidism screening in populations with sufficient iodine intake, in the percentage of newborns with TSH values 5 mU/l must be less than 3%. This study is aimed at ascertaining the prevalence of iodine deficiency among the mothers and newborns in Castellon and Valencia and, secondly, to evaluate the bearing which the day on which the sample is taken and the use of iodized antiseptics may have. Methods: The TSH value was studied in 91,853 newborns within the 2004-2006 period in Castellon and Valencia. The mean TSH values were compared considering the conditions defined by the WHO for analyzing the indicator: sampling at two days following birth and no use of antiseptics. The percentages of samples having TSH>5mU/l.were calculated and compared. Results: Among the samples having fulfilled the requirements for the analysis of the indicator, the prevalence of newborns having TSH>5 mlU/ showed a decrease from 2004 (2.2% CI95%:1.8%-2.6%), 2005 (2%; CI95%:1.6%-2.3%) and 2006 (1.7%; CI95%: 1.4%-2%). The mean TSH in samples of under 2 days was significantly higher (2.19 mlU/L; Q1-Q3: 1.35-3.40 as compared to 1.36 mlU/L; Q1-Q3: 0.78-2.21) (p< 0,001). Considering the samples taken 2 days after birth, the use of antiseptics determined a significantly higher mean TSH (1.54 mlU/L; Q1-Q3: 0.88-2.50 as compared to 1.23 mlU/L; Q1-Q3: 0.72-1.97) (p< 0,001). Conclusions: The value of the newborn thyrotropinemia indicator in Castellon and Valencia is compatible with the WHO definition for populations having a proper iodine intake. Neonatal TSH screening is a good tool for monitoring the prevalence of iodine deficiency, but the point in time of the extraction must be suitable and the use of iodized perinatal antiseptics eliminated.