Reference values for neonatal thyroid volumes in a moderately iodine-deficient area

Abstract

Background: The reference ranges of thyroid volumes in neonates vary according to the iodine status of a specific region. In different studies, it ranged between 0.47 and 1.62 ml. It has been previously shown that Bursa city was a moderately iodine-deficient area. We therefore aimed at determining normal reference ranges of neonatal thyroid volumes in our moderately iodine-deficient area. Methods: In this cross-sectional study, thyroid volumes of 100 healthy fullterm neonates (51 boys and 49 girls; mean gestational age 38.9 +/- 1.1 weeks; and mean birth-weight 3370 +/- 446 g) were measured during the first week of life using thyroid ultrasonography. These data were compared with the gestational age, birth weight, gender, and TSH values of neonates as well as with maternal factors such as gestational diabetes, preeclampsia, smoking, medication use, and heart disease. Results: All blood samples for TSH were taken during the first 5 days (mean 1.09 +/- 0.9 days). The mean TSH levels in all male and female neonates were 3.77 +/- 3.71, 4.57 +/- 3.61, and 2.93 +/- 3.66 mlU/I, respectively. This difference was statistically significant (p=0.006). Mean thyroid volumes for all male and female neonates were calculated as 0.82 +/- 0.18 (range 0.51-2.04), 0.84 +/- 0.21 (range 0.51-2.04), and 0.80 +/- 0.14 ml (range 0.58-1.30), respectively. There were no statistically significant differences in thyroid volumes with respect to gestational age, birth weight, gender, TSH values of neonates and maternal factors. Conclusion: Normal thyroid volumes in neonates vary between different regions. Local reference values should be used in thyroid volume assessment. Our results are in concordance with the literature and can be used as reference values for our region.