October - December 2006, Volume 2, Issue 4

Varlas V, Gheorghiu ML

Fetal thyroid status in normal pregnancy and premature birth euthyroid women without goitre from areas with or without iodine deficiency

Acta Endo (Buc) 2006, 2 (4): 403-418
doi: 10.4183/aeb.2006.403

Objective. This study assesses, in patients from counties with iodine deficiency (ID) and without ID, the concentrations of thyroid hormones in newborns (cord blood) and mothers at delivery, maternal and fetal thyroid volumes (less than 24 hours before delivery) and maternal urinary iodine at delivery. Another aim of this paper is to identify the interrelations between maternal and neonatal thyroid functions in the premature and full term delivery.\r\nMethods. In this study there were 83 mothers without thyroid pathology (goitre included) aged 26.51 ? 4.88 years, range 16-38 years) and their 83 newborns immediately after delivery. Four groups were identified: group A - 13 mothers from iodine sufficient area (IS) who delivered prematurely, group B - 13 mothers from iodine deficient area (ID), who delivered prematurely, group C - 38 mothers from IS area who delivered at term and group D - 19 mothers from ID area who delivered at term. The serum concentrations of TSH, total (T)T4, free (F)T4, TT3 and FT3 were evaluated by a microparticle enzyme immunoassay (MEIA). The thyroid volumes in mothers and their fetuses were measured by ultrasonography with a high resolution equipment (Accuvix XQ).\r\nResults. The values of TSH in newborns (cord blood serum), expressed as mean ? standard deviation (SD), were significantly higher in groups from ID areas (B+D) vs. groups from IS areas (A+C) (p<0.03). TSH levels were higher in group D vs. group C (6.62 ? 4.53 mU/L vs. 5.46 ? 2.83 mU/L [p<0.03]). The values of TT4 in newborns were significantly lower in group B vs group D (8.09 ? 1.68 ?g/dl vs. 9.45 ? 2.23 ?g/dl [p<0.05]), in premature group (A+B) vs term group (C+D) [p<0.007] and in groups from ID areas (B+D) vs. IS groups (A+C) vs [p<0.01]. Thyroid volumes (TV) in fetuses from IS areas (A+C) were lower than in ID areas (B+D) (p<0.002), but TV was similar in fetuses born at term or prematurely. Serum TSH levels in newborns (71.73 ? 26.54 ?g/l) were negatively correlated with maternal urinary iodine (r = -0.827, p<0.0001). Serum TSH in newborn was not correlated with maternal TSH in any group (A-D). The TV in fetuses (1.25 ? 0.1 ml) were highly correlated with TSH in newborns (r = 0.83, p<0.001), negatively correlated with maternal urinary iodine (r = -0.81, p<0.001) and correlated with maternal TV (17.12 ? 1.82 ml) (r = 0.44, p<0.02).\r\nConclusions. The status of the thyroid hormones and thyroid volumes in the newborn was dependent on the severity of iodine deficiency and in a less proportion on prematurity. The fetus is more sensitive to iodine deficiency than the mother.

Keywords: iodine deficiency, neonatal period, prematurity, thyroid volume

Correspondence: Valentin Varlas, Filantropia Hospital, 11-13 Ion Mihalache, Bucharest, Romania, e-mail: valyvarlas@yahoo.com